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The Counciland the Governing Board

The Council

President

A.S. Nigavekar,Chairperson,University Grants Commission, New Delhi.

Vice-President

V.N. Rajasekharan Pillai,Vice-Chairperson,University Grants Commission, New Delhi.

Members

N. Mukunda,[Chairperson, Governing Board],Centre for Theoretical Studies,Indian Institute of Science, Bangalore.

Shishir K. Dube,Director,Indian Institute of Technology, Kharagpur.

Ashok Kumar Gupta,J.K. Institute of Applied Physics,University of Allahabad.

Kota Harinarayana,Vice-Chancellor,University of Hyderabad.

A.K. Kembhavi,IUCAA, Pune.

A.S. Kolaskar,Vice-Chancellor,University of Pune.

R.A. Mashelkar,Director General,Council of Scientific and Industrial Research,New Delhi.

G. Madhavan Nair,Secretary to the Government of India,Department of Space, Bangalore.

Rajaram Nityananda,Centre Director,National Centre for Radio Astrophysics, Pune.

Ved Prakash,Secretary,University Grants Commission, New Delhi.

S. G. Rajasekaran,The Institute of Mathematical Sciences, Chennai.

V. S. Ramamurthy,Secretary to the Government of India,Department of Science and Technology, New Delhi.

C.V. Vishveshwara,Honorary Director,Jawaharlal Nehru Planetarium, Bangalore.

The following members have served in the Council forpart of the year

Arnab Rai Choudhuri,Indian Institute of Science, Bangalore.

S. S. Dattagupta,Director, Satyendra Nath Bose National Centrefor Basic Sciences, Kolkata.

Deepak Dhar,Tata Institute of Fundamental Research, Mumbai.

G.K. Mehta,Vice-Chancellor,University of Allahabad.

Janak Pandey,Vice-Chancellor,University of Allahabad.

R.R. Pandey,Vice-Chancellor,Deendayal Upadhyay Gorakhpur University.

S. R. Rajaraman,School of Physical Sciences,Jawaharlal Nehru University, New Delhi.

Nityananda Saha,Vice-Chancellor,University of Kalyani.

S.S. Suryawanshi,Vice-Chancellor,Swami Ramanand Teerth MarathwadaUniversity, Nanded.

J.A.K. Tareen,Vice-Chancellor,University of Kashmir, Srinagar.

Professor Abdul Wahid

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Vice-chancellorUniversity of Kashmir, Srinagar.

The following members have been inducted in theCouncil during this year

Mustansir Barma,Department of Theoretical Physics,Tata Institute of Fundamental Research, Mumbai.

A.N. Basu,Vice-Chancellor,Jadavpur University, Kolkata

Vijay Khole,Vice-Chancellor,University of Mumbai.

Arvind Kumar,Centre Director, Homi Bhabha Centre for ScienceEducation, Mumbai.

S. Mukherjee,Department of Physics,North Bengal University, Darjeeling.

Deepak Nayyar,Vice-Chancellor,University of Delhi.

Amitava Raychaudhuri,Department of Physics,Calcutta University, Kolkata.

K.L. Sharma,Vice-Chancellor,University of Rajasthan, Jaipur.

Professor H.R. Singh,Vice-Chancellor,University of Allahabad.

Member Secretary

N.K. Dadhich,Director, IUCAA.

The Governing Board

Chairperson

N. Mukunda, Bangalore.

MembersShishir K. DubeAshok Kumar GuptaKota HarinarayanaA.K. KembhaviA.S. KolaskarRajaram NityanandaVed PrakashG. RajasekaranC.V. Vishveshwara

The following members have served on the GoverningBoard for part of the year

G.K. MehtaJanak Pandey

The following member has been inducted in theGoverning Board during the year

H.R. Singh

Member Secretary

N.K. Dadhich

Honorary Fellows

Geoffrey Burbidge,Centre for Astronomy and Space Sciences, U.S.A.University of California,

E. Margaret Burbidge,University of California,Centre for Astronomy and Space Sciences, U.S.A.

A. Hewish,University of Cambridge, U.K.

Donald Lynden-Bell,Institute of Astronomy,University of Cambridge, U.K.

Yash Pal, Noida.

A.K. Raychaudhuri, Kolkata.

Allan Sandage,The Observatories of Carnegie Institute of Washington,U.S.A.

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P.C. Vaidya,Gujarat University, Ahmedabad.

Visiting Professor

Russell Cannon,Anglo-Australian Observatory, Australia.

Statutory Committees

The Scientific Advisory Committee (SAC)

Abhay Ashtekar,The Pennsylvania State University, U.S.A.

Rohini Godbole,Indian Institute of Science, Bangalore.

John Hearnshaw,University of Canterbury,Christchurch, New Zealand.

Umesh C. Joshi,Physical Research Laboratory, Ahmedabad.

Alain Omont,Institut D’Astrophysique de Paris, France.

S.K. Pandey,Pandit Ravishankar Shukla University, Raipur.

T.P. Prabhu,Indian Institute of Astrophysics, Bangalore.

Ashoke Sen,Harish-Chandra Research Institute, Allahabad.

N.K. Dadhich, (Convener)IUCAA, Pune.

Users’ Committee

N.K. Dadhich, (Chairperson)IUCAA, Pune.

A.K. Kembhavi, (Convener)IUCAA, Pune.

Narayan Banerjee,Department of Physics,Jadavpur University, Kolkata

B.P. Chandra,Vice-Chancellor,Pandit Ravishankar Shukla University, Raipur.

Syed Shahid Mahdi,Vice-Chancellor,Jamia Millia Islamia, New Delhi.

N. Unnikrishnan Nair,Vice-Chancellor,Cochin University of Science and Technology, Kochi.

T. Padmanabhan,IUCAA, Pune.

T.R. Seshadri,Department of Physics and Astrophysics,University of Delhi.

The Academic Programmes Committee

N.K. Dadhich (Chairperson)T. Padmanabhan (Convener)S.V. DhurandharRanjan GuptaA. K. KembhaviRanjeev Misra (from October 1, 2004)A.N. RamaprakashVarun SahniTarun SouradeepR. SrianandK. SubramanianS. N. Tandon

The Standing Committee for Administration

N.K. Dadhich (Chairperson)A.K. KembhaviT. PadmanabhanK.C. Nair (Member Secretary)

The Finance Committee

N. Mukunda (Chairperson)P. AgarwalN.K. DadhichR. NityanandaVed PrakashA.K. Kembhavi (from 26 .05. 2004)A. Pimpale (from 19 .08. 2004)L. Chaturvedi (till 24 .07.2004)T. Padmanabhan (till 25 .05. 2004)K.C. Nair (Non-Member Secretary)

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Members of IUCAA

Academic

N.K. Dadhich (Director)T. Padmanabhan (Dean, Core Academic Programmes)A.K. Kembhavi (Dean, Visitor Academic Programmes)J. BagchiS.V. DhurandharR. GuptaR. MisraA.N. RamaprakashV. SahniTarun SouradeepR. SrianandK. SubramanianS. N. Tandon

Emeritus ProfessorJ.V. Narlikar

Scientific and Technical

T.D. Agarkar (till 30.09.2004)N.U. BawdekarS.S. BhujbalM.P. BurseS.B. Chavan (from 28.03.2005)V. ChellathuraiK.S. Chillal (from 26.08.2004)P.A. ChordiaH.K. DasS. EngineerG.B. GaikwadS.U. IngaleA.A. KohokV.B. MestryA. ParanjpyeS. K. Pathak (till on 24.12.2004)S. PonrathnamV.K. RaiH.K. SahuY. R. Thakare

Administrative and Support

K. C. Nair (Senior Administrative Officer)N.V. AbhyankarV.P. BarveS.K. DalviS.L. GaikwadB.R. GorkhaB S. GoswamiS.B. GujarR.S. JadhavB.B. JagadeS.M. Jogalekar

S.N. KhadilkarK.B. MunuswamyS.B. KuriakoseN.S. MagdumM.A. MahabalS. G. MirkuteE.M. ModakR.D. PardeshiR.V. ParmarB.R. RaoM.S. SahasrabudheV.A. SamakS.S. SamuelB.V. SawantS. ShankarD.R. ShindeV. R. SurveD.M. SusainathanA.A. SyedS.R. TarpheS.K. WagholeK.P. Wavhal

Post-Doctoral Fellows

V. K. Agrawal (from 20.07.2004)P. Chakraborty (till 13.04.2004)Priya Hasan (from 06.09.2004)H. K. Jassal (till 27.04.2004)A. Mahmood (from 01.11.2004)M. Puravankara (from 10.01.05)S. RayE. Rollinde (till 01.02.2005)G. Sarkar (till 12.07.2004)S. Sen (from 19.11.2004)C.S. Stalin (from 08.09.2004)P. SubramanianR.S. Yadav (till 16.06.2004)

Research ScholarsA.L. AhujaU. AlamS. ChakravortyH. ChandA. DeepAmir Hajian ForushaniJosily Cyraic (from 29.12.2004)G. MahajanS. MitraH. Mukhopadhyay (from 05.07.2004)T. NaskarAli Reza Rafiee (till 11.06.2004)A. RawatS. SamuiS. Sarkar (from 30.07.2004)A. S Sengupta (till 05.02.2005)Arman ShafielooJ.V. Sheth (till 20.09.2004)

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P. Singh (till 10.06.2004)M.K. Srivastava (from 29.07.2004)S. Sur (from 02.08.2004)

Temporary/Project/Contractual Appointments

A.P. Chordia (System Engineer)M.B. Ghule (Steno-Typist, CEC Project)J.A. Gupchup (Project Officer, Virtual Observatory)M. S. Kharade (Project Officer , ERNET Project)S.T. Koshti (Project Scientist, DST Project)V. Kulkarni (Scientific/Technical Assistant-I, Public Outreach Programme)P.L. Shekade (System Engineer)

N.S.Bhujbal (System Administrative Assistant) (till November 13, 2004)P. Kulkarni (Project Officer, Virtual Observatory) (till APril 8, 2004)V. Raskar (Assistant, Public Outreach Programme) (till July 5, 2004)

P. Barathe (from April 1, 2005)A. Bhujbal (from February 22 to March 2, 2005)V. Jagtap (from January 24, 2005)V. Mhaiskar (from August 30, 2004)A. Rupner (from August 30, 2004)S. Sagar (from April 1, 2005)R. Sinha (from August 2, 2004)

Part time Consultants

S. S. Bodas (Medical Services)

Long Term Visitors

Gupta Arvind

Mohan Vijay (Visiting Scientist on Deputation, from ARIES, Nainital, from 22.03.2005)

M. Sami(On leave from Department of Physics,Jamia Millia Islamia, New Delhi)

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Visiting Members of IUCAA

Visiting Associates

Z. Ahsan,Department of Mathematics,Aligarh Muslim University.

G. Ambika,Department of Physics,Maharaja’s College, Kochi.

Badruddin,Department of Physics,Aligarh Muslim University.

Bindu A. Bambah,School of Physics,University of Hyderabad

A. Banerjee,Department of Physics,Jadavpur University, Kolkata.

N. Banerjee,Department of Physics,Jadavpur University, Kolkata.

S.K. Banerjee,Department of Mathematics,Mody College of Engineering andTechnology, Lakshmangarh.

Rashmi Bhardwaj,Department of Mathematics,Guru Gobind Singh Indraprastha University,Delhi.

S.P. Bhatnagar,Department of Physics,Bhavnagar University.

Sidhartha Bhowmick,Department of Physics,Barasat Government College, Kolkata.

Satyabrata Biswas,Department of Physics,University of Kalyani.

S. Chakrabarty,Department of Physics,University of Kalyani.

D.K. Chakraborty,School of Studies in Physics,Pt. Ravishankar Shukla University, Raipur.

Subenoy Chakraborty,Department of Mathematics,Jadavpur University, Kolkata.

Deepak Chandra,Department of Physics,,S.G.T.B. Khalsa College, Delhi.

Suresh Chandra,School of Physical Sciences,Swami Ramanand Teerth Marathwada University,Nanded.

Tanuka Chatterjee (Kanjilal),Department of Mathematics,Shibpur D.B. College, Howrah.

S. Chaudhuri,Department of Physics,Gushkara Mahavidyalaya, Burdwan.

Arnab Rai Choudhuri,Department of Physics,Indian Institute of Science, Bangalore.

M.K. Das,Institute of Information and Communication,University of Delhi, South Campus.

Jishnu Dey,Department of Physics,Maulana Azad College, Kolkata.

Mira Dey,Department of Physics,Presidency College, Kolkata.

Umesh Dodia,Department of Physics,Sir P.P. Institute of Science, Bhavnagar.

D. V. Gadre,ECE Division,Netaji Subhas Institute of Technology, Delhi.

A.D. Gangal,Department of Physics,University of Pune.

S. G. Ghosh,Department of Mathematics,Birla Institute of Technology and Science, Pilani.

A.K. Goyal,Department of Physics and Astrophysics,Hans Raj College, Delhi.

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A. Gupta,Department of Physics,St. Stephen's College, Delhi

P.P. Hallan,Department of Mathematics,Zakir Husain College, New Delhi.

K.P. Harikrishnan,Department of Physics,The Cochin College, Kochi.

S.N. Hasan,Department of Astronomy,Osmania University, Hyderabad.

Ng. Ibohal,Department of Mathematics,Manipur University, Imphal.

K. Indulekha,School of Pure and Applied Physics,Mahatma Gandhi University, Kottayam.

D. Jain,Department of Physics and Astrophysics,University of Delhi

C. Jog,Department of Physics,Indian Institute of Science, Bangalore.

M. John,Department of Physics,St. Thomas College, Kozhencherri.

K. Jotania,Department of Physics,M.N. College, Visnagar.

R.S. Kaushal,Department of Physics and Astrophysics,University of Delhi.

M. Khan,Centre for Plasma Studies,Jadavpur University, Kolkata.

P. Khare,Department of Physics,Utkal University, Bhubaneswar.

Nagendra Kumar,Department of Mathematics,K.G.K. (P.G.) College, Moradabad.

A.C. Kumbharkhane,School of Physical Sciences,Swami Ramanand Teerth Marathwada University,Nanded.

V.C. Kuriakose,Department of Physics,Cochin University of Science and Technology, Kochi.

D. Lohiya,Department of Physics and Astrophysics,University of Delhi.

Usha Malik,Department of Physics,Miranda House, Delhi.

Yogesh Kumar Mathur,Department of Physics and Astrophysics,University of Delhi.

A. K. Mittal,Department of Physics,University of Allahabad.

Kalyan K. Mondal,Department of Physics,Raja Peary Mohan College, Hooghly.

S. Mukherjee,Department of Physics,North Bengal University, Darjeeling.

K.K. Nandi,Department of Mathematics,North Bengal University, Darjeeling.

U. Narain,Astrophysics Research Group,Meerut College.

S.K. Pandey,School of Studies in Physics,Pt. Ravishankar Shukla University, Raipur.

Sanjay K. Pandey,Department of Mathematics, L.B.S. College, Gonda.

P.N. Pandita,Department of Physics,North Eastern Hill University, Shillong.

K.D. Patil,Department of Mathematics,B.D. College of Engineering, Wardha.

B. C. Paul,

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Department of Physics,North Bengal University, Darjeeling.

Ninan Sajeeth Philip,Department of Physics,St. Thomas College, Kozhencherri.

S.K. Popalghat,Department of Physics,J.E.S. College, Jalna.

Anirudh Pradhan,Department of Mathematics,Hindu P.G. College, Zamania.

Lalan Prasad,Department of Physics,M.B. Government P.G. College, Nainital.

P. Vivekananda Rao,Department of Astronomy,Osmania University, Hyderabad.

Shantanu Rastogi,Department of Physics,D.D.U. Gorakhpur University.

Saibal Ray,Department of Physics,Barasat Government College, Kolkata.

L.M. Saha,Department of Mathematics,Zakir Husain College, New Delhi.

Sandeep Sahijpal,Department of Physics,Panjab University, Chandigarh.

Ravindra V. Saraykar,Department of Mathematics,Nagpur University.

Bhim Prasad Sarma,Department of Mathematical Sciences,Tezpur University.

A.K. Sen,Department of Physics,Assam University, Silchar.

T.R. Seshadri,Department of Physics and Astrophysics,University of Delhi.

K. Shanthi,Academic Staff College,University of Mumbai.

Rajendra N. Shelke,Space Research Centre,Amravati.

G.P. Singh,Department of Mathematics,Visvesvaraya National Institute of Technology,Nagpur.

H.P. Singh,Department of Physics and Astrophysics,University of Delhi.

S. Singh,Department of Physics,Deshbandhu College, New Delhi.

Yugindro Singh,Department of Physics,Manipur University, Imphal.

D.C. Srivastava,Department of Physics,D.D.U. Gorakhpur University.

P.K. Srivastava,Department of Physics,D.A.V. P.G. College, Kanpur.

P. K. Suresh,School of Physics,University of Hyderabad.

R. Tikekar,Department of Mathematics,Sardar Patel University, Vallabh Vidyanagar.

Anisul Ain Usmani,Department of Physics,Aligarh Muslim University.

R.C. Verma,Department of Physics,Punjabi University, Patiala.

...till June 2004

F. Ahmed,Department of Physics,Kashmir University, Srinagar.

B. N. Dwivedi,Department of Applied Physics,Institute of Technology, Banaras Hindu University,Varanasi.

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V. K. Gupta,Department of Physics and Astrophysics,University of Delhi.

V. H. Kulkarni,Department of Physics,University of Mumbai.

S. N. Paul,Serampore Girls’ College,Hooghly.

Bikram Phookun,Department of Physics,St. Stephen's College, Delhi.

Farook Rahman,Department of Mathematics,Jadavpur University, Kolkata.

M.C. Sabu,Department of Mathematics,Christ College, Rajkot.

From July 2004..

Pavan Chakraborty,Department of Physics,Assam University, Silchar.

Ranabir Dutt,Department of Physics,Visva Bharati University, Santiniketan.

S.S.R. Inbanathan,Department of Physics,American College, Madurai.

Sanjay Jain,Guru Premsukh Memorial College of Engineering,Delhi.

U.S. Pandey,Department of Physics,D.D.U. Gorakhpur University,

M.K. Patil,School of Physical Sciences,Swami Ramanand Teerth Marathwada Unvierstiy,Nanded.

T. Ramesh BabuDepartment of PhysicsCochin University of Science and Technology, Kochi.

R. Ramakrishna Reddy,Department of Physics,Sri Krishnadevaraya University, Anantapur.

J.P. VishwakarmaDepartment of Mathematics and StatisticsD.D.U. Gorakhpur University.

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The fifteenth batch of Visiting Associates, who were selectedfor a tenure of three years, beginning July 1, 2004.

The photographs of the following Visiting Associates from the fifteenth batch are not available: Pavan Chakraborty,Ranabir Dutt, Sanjay Jain, U.S. Pandey and Ramakrishna Reddy.

Appointments of the following Visiting Associates from the twelfth batch were extended for three years : G. Ambika,Narayan Banerjee, Subenoy Chakraborty, Sarbeshwar Chaudhuri, Sushant G. Ghosh, K.P. Harikrishnan, Chanda J. Jog,Kanti R. Jotania, R.S. Kaushal, Nagendra Kumar, Yogesh Kumar Mathur, Kamal Kanti Nandi, P.N. Pandita, Harinder PalSingh, K. Yugindro Singh, D.C. Srivastava, Pradeep Kumar Srivastava and Anisul Ain Usmani.

J.P. Vishwakarma

S.S.R. InbanathanM.K. Patil

T. Ramesh Babu

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Dean, Core Academic Programmes(T. Padmanabhan)

Head, Post-Doctoral Research(K. Subramanian)

Head, Computer Centre(A.K. Kembhavi)

Head, Library & Documentation(T. Padmanabhan)

Head, Publications(T. Padmanabhan)

Head, M.Sc. & Ph.D. Programmes(K. Subramanian)

Head, Instrumentation Laboratory(S.N. Tandon)

Organizational Structure ofIUCAA's Academic Programmes

The Director

N.K. Dadhich

Dean, Visitor Academic Programmes(A.K. Kembhavi)

Head, Visitor Facilities(V. Sahni)

Head, Associates & Visitors(A.K. Kembhavi)

Head, Recreation Centre(P. Chordia)

Head, Guest Observer Programmes(R. Srianand)

Head, Workshops & Schools(S. V. Dhurandhar)

Head, Public Outreach Programmes(T. Souradeep)

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The Director's ReportThe year began with the inauguration of the `Pulastya'building and of the IUCAA Muktangan Vidnyan Shodhika(Science Exploratorium) on June 12, 2004 by our friend andmentor, Yash Pal. The programme of the day included YashPal, Milind Watve and Dinesh Thakur, sharing theirexperience and excitement of doing science with over 500school students in the IUCAA Chandrasekharauditorium.This building was constructed from the generousdonation of Rs. 30 lakhs by Shrimati Sunitabai Deshpande,in memory of her husband, Pu. La. Deshpande, whopersonified Marathi cultural identity. Pu. La. had wishedthat there should be a free open space where young childrensimply play and give vent to their imagination, and have funwhile learning science. The name of the building is derivedfrom a star by this name in the Saptarishi constellation andit was a wonderful and befitting tribute paid to Pu. La. by hisfriend, Professor Jayant Narlikar.

I am very happy to say that MVS - the Science Exploratorium -has started very well, and has already carved out its own identityin Pune’s scientific endeavour. It is wonderful to see the sparklingeyes of children reflecting wonder and excitement as they maketoys with their own hands, which they carry home and in theprocess have good fun. That was precisely what Pu. La. hadenvisioned.

Nothing could be a happier news than the fact that thewonderful legacy of philanthropy and generosity has beencarried forward by a person who prefers to remainanonymous and has donated Rs. 20 lakhs to MVS, of whichthe first instalment of Rs.10 lakhs has been received, andthe second is to follow soon. This is indeed an excellentway of appreciating and encouraging MVS right in its firstyear of existence. I most warmly thank our philanthropistfriend for the noble gesture, and I am sure it won’t go withoutemulation and I hope to have someone to thank every year.

We began the International Year of Physics by organising aday’s conference in which four eminent scholars AbhayAshtekar, Donald Lynden-Bell, Gavin Wraith and JayantNarlikar - spoke on various aspects of Einstein’s relativisticworld. It was attended by college and university studentsas well as other interested people. We plan to end the yearwith an international conference on Einstein’s Legacy inthe new millennium, at Puri, jointly organised with UtkalUniversity and Institute of Physics, Bhubneswar, andsponsored by other institutes.

Professor Donald Lynden-Bell, a distinguishedastrophysicist, who has been a good friend and well-wisherof IUCAA right from its conception stage, celebrated theevent of his becoming an Honorary Fellow by a visit ofthree weeks. He had been a member of our ScientificAdvisory Committee and been visiting us quite regularly.On the recommendation of the Governing Board, IUCAAhas introduced a Visiting Professor scheme under which a

distinguished scientist is supposed to visit IUCAA for 2-3times in a term of 3 years, with each visit of at least 4 weeksduration. Alexi Starobinsky of Moscow State Universityand Anvar Shukurov of University of New Castle wereinvited to be Visiting Professors and both of them hadaccepted our invitation. Professor Shukurov made his firstvisit as a Visiting Professor for 4 weeks in March/April.

The installation work on the IUCAA Telescope at theGiravali site began in June 2004, and I am happy to say thatit saw the First Engineering Light on December 10, 2004. Itis certainly one of the important milestones to be happyabout. I congratulate both TTL engineers and IUCAAscientific teams on the job well done and on excellent teamwork. The telescope is expected to be fully installed by midJune 2005, and then we have to wait through the monsoonto do open sky tests. I am happy to say that we are at longlast nearing the completion of the project.

A comprehensive peer review of all the Visiting Associateswho had completed two terms was carried out during thisyear. In all 36 Associates were reviewed in four subjectcategories. The overall performance was quite satisfactoryand the grades spectrum was A+(1), A(9), A--(6), B+(6), B(5) and B -- ( 4), C(4), and other(1). A constructive feedbackfrom the recommendations of the review committees hasbeen communicated to all the reviewed Associates. I wishto specially mention S. K. Pandey of Pt. Ravi Shankar ShuklaUniversity, Raipur, and congratulate him most warmly onhis pioneering effort in observational astronomy in theuniversity sector. He has motivated and trained about halfa dozen young astronomers who are working at variousobservatories. It is by all means, a very good contributionto observational astronomy. With our telescope coming online, I hope many more students from universities will takeup observational astronomy.

As mentioned in the previous year’s report each IUCAAfaculty is expected to visit a university and give a course ofabout 10 lectures. This programme had, though, begunwith three of us visiting Universities of Rajasthan,Hyderabad, Tezpur and Guwahati, has yet to take off in fullmeasure. I hope that next year other faculty members willalso join in. Another point of strengthening interaction withuniversities is their Ph.D. students attending IUCAAGraduate School.

Let me conclude by saying that IUCAA continues tothrive on the excellent infrastructural and support facilities,which are the mark of dedication and commitment of ourscientific/technical, and administrative and support staffwho, I thank most warmly.

Naresh Dadhich

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Congratulations to ...

Ujjaini Alam

Awarded one of the `Hartle Prizes'' from the InternationalSociety on General Relativity and Gravitation for BestStudent presentation at GR17, 2004

Sanjeev Dhurandhar

Elected Fellow of the National Academy of Sciences,Allahabad.

Amir Hajian

Gold Medal for Distinguished Ph.D. work by IranianStudent in India, presented by Minister of Foreign Affairs,Islamic Republic of Iran.

Ajit Kembhavi

Elected President of the Indian Association of GeneralRelativity and Gravitation for 2004 -2005.

J. V. Narlikar

Prix Janssen Prize (2004) by the Societe Astronomique deFrance, France.

Jeevan Gaurav Puraskar from the PadmagandhaPratisthan, Nagpur.

Dr Shankar Dayal Sharma Srujan Samman from theMadhya Pradesh Hindi Grantha Akademi, Bhopal.

T. Padmanabhan

The essay `Gravity as elasticity of spacetime: a paradigmto understand horizon thermodynamics andcosmological constant" received a Honorable Mentionin the Gravity Research Foundation Essay contest, 2004.

(a) IUCAA Members

(b) IUCAA Associates

P. N. Pandita

Elected Fellow of the Indian Academy of Sciences,Bangalore.

Arnab Roy Choudhury

Elected Fellow of the Indian Academy of Sciences,Bangalore.

Sailo Mukherjee

Invited to deliver the Vaidya-Raychaudhuri EndowmentFund lecture "Cold Compact stars: A Laboratory forNew Physics" during the 23rd IAGRG meeting.

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Calendar of Events

2004

April 19 - May 28 School Students' Summer Programmeat IUCAA

May 7 IUCAA-NCRA Graduate SchoolSecond Semester ends

May 17 - June 18 Introductory Summer school on Astronomy and Astrophysicsat IUCAA

May 17 - July 2 Vacation Students' Programmeat IUCAA

August 9 IUCAA-NCRA Graduate SchoolFirst semester begins

September 27- International Virtual Observatory Alliance (IVOA)October 1 - Interoperability Meeting

at IUCAA

October 5-9 Workshop on High Performance Computingat IUCAA

October 25-29 Workshop on Astrophysics forCollege Teachers and Researchersat Kumaun University, Nainital

October 27- Workshop on Strings and CosmologyNovember 1 at IUCAA

December 6-10 Workhop on Interstellar Mediumat Bangalore University

December 10 IUCAA-NCRA Graduate SchoolFirst semester ends

December 29 Foundation Day

2005

January 3 IUCAA-NCRA Graduate SchoolSecond semester begins

January 2 Special Relativity Centenary Meetingat IUCAA

January 31- Workshop on Observational Astronomy with Small TelescopesFebruary 4 at V.R. College, Nellore

February 27 Open Day

February 28 National Science Day

ACADEMIC PROGRAMMES

The following description relates to research workcarried out at IUCAA by the Core Academic Staff,Post-Doctoral Fellows and Research Scholars. Thenext section describes the research work carried outby Visiting Associates of IUCAA using the Centre’sfacilities.

(I) RESEARCH BYRESIDENT MEMBERS

The research described below is grouped area-wise.The name of the concerned IUCAA member ap-pears in italics.

Quantum Theory and Gravity

Holographic structure of Einsteingravity

If we treat the macroscopic spacetime as analogousto a continuum solid and the unknown microscopicstructure of spacetime as analogous to the atomicstructure — a paradigm originally suggested bySakharov — then it is possible to gain some impor-tant insights into the possible nature of quantumgravity.

First of all, one notes that the macroscopic de-scription of a solid uses concepts like density, stressand strain, bulk velocity, etc., none of which caneven be usefully defined in the microscopic descrip-tion. Similarly, variables like metric tensor, etc.may not have any relevance in quantum gravity.

Second, the quantum theory of a spin-2 field(“graviton”) will be as irrelevant in quantum grav-ity, as the theory of photons in providing any in-sight into the electronic structure of atoms.

Third, the symmetries of the continuum de-scription (e.g., translation, rotation, etc.) will beinvalid or will get strongly modified in the micro-scopic description. A naive insistence of diffeomor-phism invariance in the quantum gravity, based onthe classical symmetries, will be as misleading asinsisting on infinitesimal rotational invariance of,say, an atomic crystal lattice. In short, the vari-ables and the description will change in an (as yetunknown) manner. It is worth remembering thatthe Planck scale (1019 GeV) is much farther awayfrom the highest energy scale we have in the lab(102 GeV) than the atomic scale (10−8 cm) wasfrom the scales of continuum physics (1 cm).

It is, therefore, useful to investigate generalfeatures of quantum microstructure, which couldbe reasonably independent of the detailed theoryof quantum spacetime — whatever it may be. T.

Padmanabhan was pursuing such an approach —which could be called a thermodynamic approachto spacetime dynamics, to be distinguished fromthe statistical mechanics of microscopic spacetimes— in the recent years. This procedure throws lighton several peculiar features of gravity (which haveno explanation in the conventional approach) andprovides a new insight in e.g., interpreting generalcoordinate transformations.

In general relativity, one can distinguish be-tween the kinematics (“spacetime tells matter howto move”) and the dynamics (“matter tells space-time how to curve”). The geometric descriptionof the kinematics arises quite elegantly from theprinciple of equivalence. To obtain the dynam-ics, which depends on the choice of the actionprinciple, one uses the Einstein-Hilbert LagrangianLEH ∝ R, which has a formal structure LEH ∼R ∼ (∂g)2 + ∂2g. If the surface term obtained byintegrating Lsur ∝ ∂2g is ignored (or, more for-mally, cancelled by an extrinsic curvature term)then the Einstein’s equations arise from the vari-ation of the bulk term Lbulk ∝ (∂g)2, which is thenon-covariant Γ2 Lagrangian.

On closer inspection, this procedure raises sev-eral questions. To begin with, it does not have theelegance or uniqueness, possessed by the geometricdescription of the kinematics. Second, in no otherfield theory (including Yang-Mills), does the sym-metries of the theory lead to a Lagrangian involv-ing second derivatives of the dynamical variables;it is clearly unusual. Third, the action is a win-dow to the quantum theory and one might suspectmost of the difficulties in quantising gravity mightbe due to quantising the wrong action functionalbased on wrong fundamental variables; it is possi-ble that continuum spacetime is like an elastic solidand what we should be quantising is the ‘atomicstructure’ of spacetime. Finally, in using Lbulk toobtain the dynamics, we are also assuming tacitlythat the gravitational degrees of freedom are thecomponents of the metric and they reside in the vol-ume V. But recall that, around any event, one canchoose a local inertial frame so that Lbulk ∝ (∂g)2

vanishes, since ∂g vanishes. On the other hand,one cannot make Lsur ∝ ∂2g part to vanish by anychoice of coordinates suggesting that the true de-grees of freedom of gravity for a volume V reside inits boundary ∂V. (This is most easily seen by eval-uating the action in Riemann coordinates in whichthe bulk term vanishes and only Lsur contributes).This point of view is also strongly supported by thestudy of horizon entropy, which shows that the de-grees of freedom hidden by a horizon scales as thearea and not as the volume.

If this view is correct, it must be possible toobtain the dynamics of gravity from an approachwhich uses only the surface term of the Hilbert ac-

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tion. Indeed, Padmanabhan has shown that suit-able variation of the surface term will lead to Ein-stein’s equations and that one does not need thebulk term at all !. What is more, he can obtainthe surface term itself from general considerationsthereby providing a new, self-contained and holo-graphic approach to gravity.

In this approach, the action functional for thecontinuum spacetime has the form Atot = Asur +Amatter in which matter lives in the bulk V, whilethe gravity contributes on the boundary ∂V. Whenthe boundary has a part which acts as a horizon fora class of observers, one demands that the actionshould be invariant under virtual displacements ofthis horizon. This leads to Einstein’s theory! SinceAsur is related to the entropy, its variation, whenthe horizon is moved infinitesimally, is equivalent tothe change in the entropy dS due to virtual work.The variation of the matter term contributes thePdV and dE terms and the entire variational prin-ciple is equivalent to the thermodynamic identityTdS = dE + PdV applied to the changes when ahorizon undergoes a virtual displacement. (In thecase of spherically symmetric spacetimes, for ex-ample, Padmanabhan has previously demonstratedexplicitly that the Einstein’s equations follow fromthe thermodynamic identity applied to horizon dis-placements.)

The result also shows that Einstein’s theoryhas an intrinsic holography. The standard descrip-tion is in terms of Lbulk and we have now shownthat it has a dual description in terms of Lsur. Itwas noticed earlier by Padmanabhan that there isa remarkable relation between these two terms

√−gLsur = −∂a

(gik

∂√−gLbulk

∂(∂agik)

), (1)

which has no explanation in standard approach.The current analysis shows that the horizon en-tropy and resulting thermodynamics for localRindler observers (based on Lsur) leads to the samedynamics as that based on Lbulk, showing their in-terdependence.

Given the true microscopic degrees of freedomof spacetime (say, qi) and an action Amicro describ-ing them, the integration of exp(−Amicro) over qi,should lead to the term exp(−Asur) as well as tothe concept of metric tensor, which is a macro-scopic concept in the continuum limit, analogousto, say, the density field of a solid. In the variationxa → xa = xa + ξa, the ξa(x) is similar to the dis-placement vector used, for example, in the study ofelastic solids. The true degrees of freedom are someunknown ‘atoms of spacetime’ but in the contin-uum limit, the displacement xa → xa = xa + ξa(x)captures the relevant dynamics, just like in thestudy of elastic properties of the continuum solid.

Further, it can be shown that the horizons in thespacetime are similar to defects in the solid so thattheir displacement costs entropy. The demand thataccelerated observers with horizons should be ableto do consistent physics, with variables accessibleto them, turns out to be as powerful in determiningthe dynamics of gravity, as the principle of equiv-alence (applied to inertial observers) was in deter-mining the kinematics of gravity.

Cosmological constant and vacuumfluctuations

The conventional discussion of the relation betweencosmological constant and vacuum energy densityis based on evaluating the zero point energy ofquantum fields with an ultraviolet cutoff and usingthe result as a source of gravity. Any reasonablecutoff will lead to a vacuum energy density ρvac

which is unacceptably high.This argument, however, is too simplistic since

the zero point energy — obtained by summing overthe (1/2)hωk — has no observable consequence inany other phenomena and can be subtracted out byredefining the Hamiltonian. The observed non triv-ial features of the vacuum state of QED, for exam-ple, arise from the fluctuations (or modifications)of this vacuum energy rather than the vacuum en-ergy itself. This was, in fact, known fairly early inthe history of cosmological constant problem and,in fact, is stressed by Zeldovich who explicitly cal-culated one possible contribution to fluctuations af-ter subtracting away the mean value. This suggeststhat we should consider the fluctuations in the vac-uum energy density in addressing the cosmologicalconstant problem.

This fact alone, however, would not havehelped. The vacuum expectation values in questionare all ultraviolet divergent and will — normally —scale as a suitable power of the UV-cutoff, Luv. Ifthe energy density behaves as ρ ∝ L−4

uv , the fluc-tuation ∆ρ will also scale as L−4

uv , since that is thedominant scale in the problem; so the cosmologicalconstant will still come out too large. Another dif-ficulty is that, at least formally, the ground state isan energy eigenstate and it will have no dispersionin the energy.

T. Padmanabhan has recently shown thatthere is a nice manner in which de-sitter spacetimecircumvents these difficulties and leads to the cor-rect value for the cosmological constant. The keynew ingredient arises from the fact that the prop-erties of the vacuum state (or, for that matter, anyquantum state in field theory) depends on the scaleat which it is probed. It is not appropriate to askquestions without specifying this scale. (This, insome sense, has been the key lesson from renormal-

16

isation group.) If the spacetime has a cosmologicalhorizon which blocks information, the natural scaleis provided by the size of the horizon, LH , and weshould use observables defined within the accessi-ble region. The operator H(< LH), correspondingto the total energy inside a region bounded by acosmological horizon, will exhibit fluctuations ∆E,since vacuum state is not an eigenstate of this oper-ator. The corresponding fluctuations in the energydensity, ∆ρ ∝ (∆E)/L3

H = f(Luv, LH) will nowdepend on both the ultraviolet cutoff Luv as well asLH . We now see an interesting possibility of bootstrapping: When used as the source of gravity, this∆ρ should lead to a spacetime with the horizonsize LH , which, in turn, requires us to compute ∆ρusing LH as the infrared cutoff scale. Note that,it is the existence of a cosmological horizon at LH

which provides a clear justification for using thislength scale in computing the energy fluctuations.This leads to a value for ∆ρ different from L−4

uv ,since we now have two length scales in the problem.This bootstrapping will lead to a relation between∆ρ, Luv and LH . Padmanabhan has shown thatthis relation is ∆ρ ∝ (LuvLH)−2 ∝ H2/G if wetake the ultraviolet cut off at Planck length. Thatis precisely what we need.

In fact, while the energy density associatedwith Planck length is ρuv ∝ L−4

P and the en-ergy density associated with the Hubble length isρir ∝ L−4

H (where LH = 1/H), the observed valueof the dark energy density is quite different fromeither of these and is close to the geometric meanof the two: ρvac '

√ρuvρir. This bootstrapping

condition leads naturally to an effective dark en-ergy density ∆ρ ∝ (LuvLH)−2 ∝ H2/G, which isprecisely the observed value.

Classical Gravity

There is more to gravity than gravi-tons

The two classical fields — electromagnetism andgravity — are described by a vector field and sec-ond rank symmetric tensor field, respectively. Con-siderations based on Lorentz group suggest inter-preting them (when suitable restrictions are im-posed) as corresponding to massless spin-1 andspin-2 fields. The vector field Ai couples to aconserved current Ji but does not contribute tothis current. (That is, the photon does not carrycharge.) In contrast, the tensor field couples tothe energy momentum tensor, since the field itselfcarries energy, it has to couple to itself in a nonlinear fashion. (The situation is similar to Yang-Mills fields which carry isotopic charge and hence

are non linear.) It should, therefore, be possible toobtain a correct theory for gravity by starting witha massless spin-2 field hab coupled to the energymomentum tensor Tab of other matter sources tothe lowest order, introducing self-coupling of hab

to its own energy momentum tensor at the nextorder and iterating the process. This will lead to acompletely field theoretic description of gravity ina Minkowski background and is conceptually quiteattractive.

This attempt has a long history. The fieldequation for a free massless spin-2 field was orig-inally obtained by Fierz and Pauli. The first at-tempt to study the consequences of coupling thisfield to its own energy momentum tensor seems tohave been by Kraichnan in unpublished work donein 1946-47. The first published attempt to derivethe nonlinear coupling is by Gupta (1954), andKraichnan published some of his results soon af-ter. Feynman has provided a derivation in his Cal-tech lectures on gravitation during 1962-63. Theproblem was re-addressed by a clever technique byDeser.

Virtually, all these approaches claim to ob-tain not only Einstein’s field equations but alsothe Einstein-Hilbert action. This result is widelyquoted in literature and, at first sight, seems em-inently reasonable. However, deeper examinationby Padmanabhan raises several disturbing ques-tions, if the above result is really valid.

First, in the conventional derivations, the finalmetric arises as gab = ηab+λhab where λ ∝

√G has

the dimension of length and hab has the correct di-mension of (length)−1 in natural units with h = c =1. The iteration is in powers of λ, starting from thezeroth order lagrangian L0 ' (∂h)2 for spin-2 field,which has the dimension of (length)−4. The finalresult in all the published works is the Einstein-Hilbert Lagrangian LEH = (1/4λ2)R. Since thescalar curvature has the structure R ' (∂g)2 +∂2g,substitution of gab = ηab +λhab gives to the lowestorder: LEH ∝ λ−2R ' (∂h)2 + λ−1∂2h. Thus, thefull Einstein-Hilbert Lagrangian is non-analytic inλ! It is impossible to start from (∂h)2, do a honestiteration on λ, and obtain a piece which is non-analytic in λ. At best, one can hope to get thequadratic part of LEH , which gives rise to the Γ2

action but not the four-divergence term involving∂2g.

Further, to carry out this programme, oneneed to identify the energy momentum tensor TG

ab

for the graviton field hab order by order in the cou-pling constant. The same textbooks which assertthat Einstein’s theory can be obtained by couplinghab to itself self consistently will also state in someother section that gravitational field does not havea well defined energy momentum tensor! It will be

17

rather strange if a unique energy momentum ten-sor exists for gravitational field order by order inthe perturbation series but somehow “disappears”when all the terms are summed up.

None of the previous derivations addressesthese issues and most of them downplays the roleof assuming general covariance. All these attemptsmake different tacit assumptions and it is difficultto judge which of these derivations can be thoughtof as “from first principles” in the sense that itis completely independent of our knowledge of theend result. This difficulty becomes apparent whenone follows the details of many of these derivations.The technology used is very strongly influenced bythe known final result. In particular, the fact thatthe action for the final theory contains the secondderivatives of the field and is always put in by hand.

T. Padmanabhan has now critically re-examined the previous attempts and provided adetailed analysis aimed at clarifying the situation.First, he proves that it is impossible to obtainthe Einstein-Hilbert (EH) action, starting from thestandard action for gravitons in linear theory anditerating repeatedly. At best, one can only hopeto obtain the remaining, quadratic, part of theEH Lagrangian (viz., the Γ2 Lagrangian) if no ad-ditional assumptions are made. Second, he usesthe Taylor series expansion of the action for Ein-stein’s theory, to identify the tensor Sab, to whichthe graviton field hab couples to the lowest order.Padmanabhan shows that the second rank tensorSab is not the conventional energy momentum ten-sor T ab of the graviton and provides an explana-tion for this feature. Third, he constructs the fullnonlinear Einstein’s theory with the source beingspin-0 field, spin-1 field or relativistic particles byexplicitly coupling the spin-2 field to this secondrank tensor Sab order by order and summing upthe infinite series. Finally, he constructs the the-ory obtained by self consistently coupling hab tothe conventional energy momentum tensor T ab or-der by order and show that this does not lead toEinstein’s theory. The analysis proves that the ge-ometrical structure of Einstein gravity has morephysical content than that obtained by iterating agraviton field.

In how many dimensions should grav-ity live ?

Gravity is universal. It interacts with all particlesincluding massless ones, it is present everywhereand its range is infinite. Zero mass particle is char-acterized by the property that it moves with thesame velocity relative to all observers so that itsveolcity cannot change even when a force acts onit. Hence its interaction with gravity cannot be

facilitated through the Newton’s second law of mo-tion, which determines how the velocity of a parti-cle changes under the action of a force.

Particles of light, photons, are examples ofzero mass particles which occur freely in nature.Their existence requires a new mechanics becausethe Newtonian mechanics cannot admit a velocitywhich is the same for all observers as the law ofaddition of velocities is w = u + v. Not only is anew mechanics required, so also a new theory ofgravity in which light feels gravity and yet its ve-locity does not change. The only way this couldhappen is that gravity should curve the space andlight should freely propagate in the curved space.Gravity then becomes the property of geometry ofspacetime. The new mechanics synthesizes spaceand time into one entity spacetime. The formeris the Einstein’s theory of gravitation, known asgeneral relativity (GR) while the latter is the Ein-steinian mechanics, known as special relativity.

The curvature of spacetime should by itself de-termine the dynamics of gravitational field. And itdoes. Riemann curvature tensor (which involvessecond and square of first derivative of the space-time metric) satisfies the Bianchi differential iden-tities which on contraction leads to the divergencefree second rank symmetric tensor involving con-traction of the Riemann tensor. This tensor is asecond order differential operator on the metric gab,which should be equated to a second rank sym-metric tensor serving as the source for the fieldand a constant of integration relative to covariantderivative. Thus, on the right hand side one hasenergy momentum tensor for matter with vanish-ing divergence ensuring conservation of energy andmomentum and the constant of integration is whatis called the cosmological constant. It naturallyarises as a new constant of the Einstein’s gravity.One, thus, obtains the Einstein’s equation for grav-itation which is in principle valid in any dimensionsgreater than 2 (the minimum dimensions requiredto define curvature). This has led N. Dadhich toask the question: In how many dimensions doesgravity live? It is well known that the minimumnumber of dimensions required to fully realise itsdynamics is 4 (3-space and 1-time). That means4 dimensions are necessary; are they sufficient tofully describe gravity? This depends upon in howmany space dimensions does matter live. Going bythe dynamics of the matter field, it is all realisedin 3 space dimensions and hence there is no com-pelling reason to take matter to dimensions greaterthan 3.

Gravitation and the electromagnetism are theonly two long range classical fields. The crucial dif-ference between them is that the latter is bipolarwhile the former is unipolar, because gravitational

18

charge is the matter energy density which is alwayspositive. All macroscopic objects down to an atomare electrically neutral. This means, there cannotoccur an isolated electric charge, which will alwaystry to neutralise itself by attracting the oppositecharge. This should be true for gravity as well.How can one neutarlise the always positive gravi-tational charge of matter/energy density, but neu-tralise it must? The only thing which has not yetbeen tapped is the gravitational field it produces.The charge neutrality could be achieved if and onlyif gravitational field has gravitational charge of op-posite polarity. The field energy must, therefore, benegative and hence the universal force must alwaysbe attractive. It is the simplest and most directexplanation of why gravity is always attractive.

It should be noted that negative charge of thefield is non-localizable and is distributed all overthe space. This means a vector theory like theMaxwell’s electromagnetic theory will not be suf-ficient to describe gravity. A more general entitythan a vector will be required, which could takeinto account distributional character of the nega-tive gravitational charge. A tensor theory is re-quired. The situation is even more complex for thefield is spread all over the space so that it couldbe best defined as a property of space itself. Thisaugurs very well with universal charachter of grav-ity demanding its geometric description. The over-all charge neutrality will be achieved only whenwe integrate negative charge (field) over the en-tire space. That is, positive mass of an isolatedbody will be completely neutralized by negative en-ergy of its field integrated all over the space. How-ever, in the local neighbourhood of the body, therewill be charge imbalance with dominance of pos-itive charge. Therefore, gravity must propagateoff the 3-brane in the extra dimension in the lo-cal neighbourhood. But it should not be able to godeep enough because as it propagates its strengthdiminishes, and larger and larger negative chargecoming in through increase in its support space onthe brane. Gravity will thus have to propagate inthe extra fifth dimension though not deep enough.

There is yet another physical argument forgravity in extra dimension. It is clear that the grav-ity is a self interactive force. In GR, the metric ten-sor is the gravitational potential. The first iterationwill require inclusion of square of first derivative ofthe metric in the field equation. This is indeedthe case for the Einstein equation which followsfrom the Riemann curvature involving second andsquare of first derivative of the metric. The Ein-stein gravity is, therefore, self interactive which isits distinguishing feature. However, it only includesthe first iteration. Self interaction has to be eval-uated at all orders unless some physical property

stops the iteration chain.To go to the second iteration will mean to in-

volve square of the Riemann and its contractions.This will, however, also square second derivative,which is the highest order of derivative. If thehighest order of derivative does not occur linearly,the equation cannot have unique solution for aquadratic or higher powers will yield two or moredifferential equations. For the equation to admitunique solution, the second derivative must occurlinearly. The differential geometry does provide aspecific combination of square of Riemann, Ricciand Ricci scalar, called the Gauss - Bonnet combi-nation, that yields the quasi linear equation. Thatis, square of second derivative terms get perfectlycancelled out. The second iteration could, thus, beaccounted for by inclusion of the Gauss - Bonnetterm. But this term makes non-zero contributiononly in dimensions greater than 5. This means thatthe second iteration of self interaction of gravitytakes it to the extra fifth dimension.

The next question is where does the iterationchain terminate? As we have argued earlier that allmatter remain confined to the 3-brane and hence,the five dimensional bulk spacetime is completelyfree of matter and has purely geometric supportin the Guass - Bonnet term. It would, hence, behomogeneous and isotropic and will have vanish-ing Weyl curvature and would be either de Sitter(dS) or anti de Sitter (AdS). Since it is gravita-tional field which has negative energy density andleaks into the extra dimension, it should be AdSwith negative energy density. Since Weyl curva-ture is zero, there is no free gravity to propagateout in the next higher dimension and thus, termi-nates the iteration chain. For the matter confinedto the 3-brane, for the realization of full dynamicsof gravity, a 5-dimensional AdS bulk spacetime isrequired harbouring our 4-dimensional universe asa hypersurface.

Dadhich has thus argued, purely from classi-cal standpoint, that 4 dimensions are necessary butnot sufficient for full realization of gravitational dy-namics. It is remarkable that this leads to the samemodel of brane world gravity as the popular stringtheory inspired Randall - Sundrum model.

Gravitational Waves

Overview and recent advances:

Einstein’s theory of general relativity predicts theexistence of gravitational waves (GW) and thatthey share certain properties of electromagneticwaves. However, GW differ from electromagneticwaves in several fascinating ways and these differ-

19

ences make it likely that they might bring us newinsights and give us a new picture of the universe.

The existence of GW was established severalyears ago by Hulse and Taylor. They observed thatthe decay in orbit of the binary pulsar PSR 1913+ 16 is within a fraction of a percent of that pre-dicted by the general theory of relativity. However,the direct detection of GW has not been achievedso far, but is never-the-less important for gainingnew astrophysical information about our universehitherto unavailable from other astronomical win-dows.

The recent technological advances in interfer-ometric techniques has led to the development ofextremely sensitive laser interferometric gravita-tional wave observatories around the world. Mostof the interferometric detectors are either in oper-ation or nearing operation. The LIGO project ofthe US consists of three detectors: two of 4 kmarmlength and one of 2 km armlength in Hanfordand Louisiana; the French-Italian Virgo project isa 3 km detector near Pisa, Italy which will soonbe conducting its first science run; the German-British GEO project is running a 600 metre de-tector near Hannover, Germany and the Japanesedetector TAMA300, a 300 metre detector has beenin operation for several years now. The Japanesealso have plans to construct a 3 km armlength de-tector (LCGT). Australia is also in the ring and inChina too there is a proposal for an undergrounddetector which is supposed to operate at low fre-quencies below 10 Hz. Several of these detectorsare getting close to design sensitivities and somehave already taken data and are setting interestingupper limits on the GW strain h in the frequencyrange from 100 Hz to kHz. The peak design sensi-tivity in the spectral density for the initial detec-tors is hrms ∼ 10−23Hz−1/2 near 100 Hz. All theseefforts gives us hope that gravitational waves maysoon be detected, opening new horizons in physicsand astronomy. GW are produced by objects pre-dominantly having a time-varying mass quadrupolemoment. To the leading order in v/c, where v isthe typical velocity of the source and c the speedof light, the GW strain amplitude (or the metricperturbation) h is proportional to the second timederivative of the mass quadrupole moment. Thesewarpages in the fabric of space-time would travelaway from the source with the speed of light. Thechange in the distance ∆L between freely fallingmasses at a distance L is ∆L ∼ hL. The GW strain(metric perturbation) is infinitismally tiny becauseof the extremely weak coupling of gravity to mat-ter. For instance, for a system of binary neutronstars at a distance of 100 Mpc, the GW strain thatis produced minutes before they coalesce is of theorder of h ∼ 10−23. Because of the tiny measure-

ments involved in detecting GW, the experimentis an extremely difficult enterprise. Nevertheless,strain sensitivities of this order are being achievedby the current detectors, notably the LIGO detec-tors of the US.

The future for GW research looks bright: de-velopmental work on advanced detectors has al-ready begun whose sensitivity will be about tentimes better than the present detectors. Such de-tectors should be able to detect neutron star -neutron star coalescences out to several hundredMpc. blackhole-blackhole binaries are also goodcandidates for detection by these detectors if theirmasses are smaller than about 10M. Black-holeswith larger masses, like at the centres of galaxies,emit stronger signals but at low frequencies, below1 Hz. Here the ground-based detectors are insensi-tive because of the gravity gradient noise which isdifficult to eliminate on Earth.

The solution is to build a detector in space.The Laser Interferometric Space Antenna - LISA -is a space-based detector of GW designed to studylow frequency GW in the range 10−4 Hz to 1 Hz.The LISA is a NASA and ESA project and will belaunched in early next decade. LISA consists ofthree spacecraft located 5 million kilometres apartforming an equilateral triangle. The spacecraft aremaintained drag-free by a complex system of ac-celerometers and micro-propellers. Each spacecraftrevolves in its own heliocentric orbit. The centreof the equilateral triangle is located on the eclip-tic and lags 20 degrees behind the Earth. Thespacecraft rotate in a circle drawn through the ver-tices of the triangle and the LISA constellation asa whole revolves around the Sun. Each spacecrafthouses two lasers and two telescopes each point-ing at the two distant spacecraft. The light sentout by a laser in one spacecraft is received by thetelescope on the distant spacecraft. The incom-ing light from the distant spacecraft is then mixedwith the in-house laser and the differential phase isrecorded. This defines one elementary data stream.There are, thus, six elementary data streams whichare formed by going clockwise and anti-clockwisearound the LISA triangle. Suitable combinationsof these elementary data streams can be used tooptimally extract the GW signal from the instru-mental noise.

The astrophysical sources that LISA could ob-serve include galactic binaries, extra-galactic super-massive blackhole binaries and coalescences, andstochastic GW background from the early uni-verse. Coalescing binaries are one of the impor-tant sources in the LISA frequency band. Theseinclude galactic and extra galactic stellar mass bi-naries, and massive and super massive black-holebinaries. Massive blackhole binaries are interest-

20

ing both from the astrophysical and theoreticalpoints of view. Coalescences of massive black-holes from different galaxies after their merger dur-ing growth of the present galaxies would provideunique new information on galaxy formation. Co-alescence of binaries involving intermediate massblackholes could help understand the formationand growth of massive blackholes. The super mas-sive blackhole binaries are strong emitters of GWand these spectacular events can be detectable be-yond red-shift of z = 1. These systems would helpto determine the cosmological parameters indepen-dently. And, just as the cosmic microwave back-ground is left over from the Big Bang, so too shouldthere be a background of gravitational waves. Un-like electromagnetic waves, gravitational waves donot interact with matter after a few Planck timesafter the Big Bang, so they do not thermalize.Their spectrum today, therefore, is simply a red-shifted version of the spectrum they formed with,which would throw light on the physical conditionsat the epoch of the early universe.

The extended hierarchical search

The most important recent development was theperformance of the hierarchical code in searchingfor inspiraling binaries on real data - the data fromthe second science run (S2) of the LIGO detectors.The usual (flat) search which finely scans the pa-rameter space, was made more efficient by a factorbetween 6 and 10. The code, however, still needsto be optimised which should yield even a higherefficiency factor.

Inspiraling binaries are the most promisingsources for both interferometric detectors as wellas for LISA. Their waveform can be well mod-elled in terms of post-Newtonian expansions and somatched filtering methods are optimal for extract-ing the signal from the noise. The flat search fordetecting inspiraling binaries is a one step search,which utilises closely spaced templates in the pa-rameter space. Although performing a rigorous andsatisfactory search of the parameter space, this ap-proach entails very large computational cost. Amore efficient method can be employed when theoccurence of the signal in the data is deemed tobe a rare event. In such a case, one is mostly sift-ing through noise. In the first (trigger) stage ofthe algorithm, a coarse search is carried out andthe candidate events are followed up with a finesearch in the neighbourhood of such events. Forthe parameter space of spinless binaries, a two stephierachical search is sufficient.

A hierarchical search was performed for thefirst time by S. D. Mohanty in searching for inspi-raling binary signals several years ago. The hier-

archy was limited to the two masses of the binarystars. A. S. Sengupta and S. V. Dhurandhar and A.Lazzarini extended the hierarchy to a third param-eter: the time-of-arrival. This work is within theLigo Science Collaboration (LSC). The strategy isbased on the fact that the inspiraling binary GWsignal (the chirp signal) contains most of its powerat low frequencies - the power in the chirp signalfalls of as f−7/3. Because of this property, the chirpsignal can be cut-off at quarter of the usual up-per cut-off frequency without losing too much sig-nal power, so that the hierarchy over masses is notseverely compromised. The data is then sampledat the reduced Nyquist frequency, saving the com-putational cost of the FFTs in the trigger stageby about the same factor. The cost gain factorover a flat search is about 65 for the initial LIGOnoise power spectral density for stationary Gaus-sian noise. For real data (S2 run) the factor comesdown to about 10 which is still substantial.

The extended search algorithm was validatedand a code was written following LIGO specifica-tions within the LIGO Algorithms Library (LAL)and the LIGO Data Analysis System (LDAS) en-vironments. The code was first tested on a standalone machine and then in the LDAS environment.Finally the code was run on real data.

The second science run (S2) of the LIGO wascarried out for two months from February 14 toApril 14, 2004. Pre-conditioned data, suitable foranalysis can be queried from these LDAS sites viaworld wide web (WWW) remotely. At IUCAA, adata analysis software was written to analyze theLIGO data for detecting signatures of GW frominspiraling binaries. The software is written in aformat that allows it to be remotely run on mas-sively parallel Beowulf clusters available at LDASsites remotely via WWW. For validating the codethe following procedure was followed: one takesdata stretches from LIGO detectors in which ex-pected GW signals from inspiraling binaries are ei-ther added by hand (software injection) or the mir-rors of the interferometer are shaken to mimic itsbehavior in the presence of GW (hardware injec-tion). In either case, the data is parsed throughthe analysis pipeline and one hopes to make a de-tection at the end of the pipeline. The injection pa-rameters are known before hand and so it is easy tocheck that the physical parameters correspondingto these detections match the injection parametersas closely as possible.

The detection efficiency of the code was alsotested using a hypothetical uniform distribution ofsources and comparing the detections with the falsealarm rate as found by the code. The detection ef-ficiency compared favourably with the flat searchcode while at the same time reducing the compu-

21

tational cost several times.Inspiraling compact binaries are promising

sources of gravitational waves for ground andspace-based laser interferometric detectors. Thetime-dependent signature of these sources in thedetectors is a well-characterized function of a rel-atively small number of parameters; thus, the fa-vored analysis technique makes use of matched fil-tering and maximum likelihood methods. As theparameters that characterize the source model arevaried so do the templates against which the detec-tor data are compared in the matched filter. Forsmall variations in the parameters, the output ofthe matched filter for the different templates areclosely correlated. Current analysis methodologysamples the matched filter output at parametervalues chosen so that the correlation between suc-cessive samples is 97%. Correspondingly, with theadditional information available with each succes-sive template evaluation is, in a real sense, only 3%of that already provided by the nearby templates.The reason for such a dense coverage of parameterspace is to minimize the chance that a real sig-nal, near the detection threshold, will be missedby the parameter space sampling. S. Mitra, S. V.Dhurandhar and S. Finn describe a straightforwardand practical way of using interpolation to takeadvantage of the correlation between the matchedfilter output associated with nearby points in theparameter space to significantly reduce the num-ber of matched filter evaluations without sacrific-ing the efficiency with which real signals are recog-nized. Because the computational cost of the anal-ysis is driven almost exclusively by the matchedfilter evaluations, the reduction in the number oftemplates translates directly into an increase incomputational efficiency. And the computationalcost of the analysis is large, the increased efficiencytranslates also into an increase in the size of the pa-rameter space that can be analyzed and, thus, thescience that can be accomplished with the data.

As a demonstration, the present “dense sam-pling” analysis methodology is compared with theproposed “interpolation” methodology, restrictedto one dimension of the multi-dimensional anal-ysis problem. It is found that the interpolatedsearch reduces by 25% the number of filter eval-uations required by the dense search with 97% cor-relation to achieve the same efficiency of detectionfor a given expected number of false alarms. Gen-eralized to the two dimensional space used in thecomputationally-limited current analyses this sug-gests a factor of two increase in computational ef-ficiency; generalized to the full fifteen dimensionalparameter space that characterizes the signal asso-ciated with an eccentric binary system of spinningneutron stars or blackholes, it suggests a factor of

75 increase in computational efficiency.

Stability of the LISA configuration

The joint NASA-ESA mission LISA relies cruciallyon the stability of the three spacecraft constella-tion. Each of the spacecraft is in heliocentric orbitsforming a stable triangle. In order for LISA to op-erate successfully, it is crucial that the three space-craft which form the hubs of the laser interferome-ter in space maintain nearly constant distances be-tween them. The distance between any two space-craft is ∼ 5 × 106 km which must be maintainedduring the LISA’s flight. However, in order to thor-oughly study optical links and light propagation be-tween these moving stations, one requires detailedanalysis of the LISA configuration. S. V. Dhurand-har, R. Nayak, S. Koshti and J-Y Vinet have goneto the basics to examine the principles of a stableformation flight and also to present an analyticaltreatment of the problem in the context of LISA.They first study three Keplerian orbits around theSun with small eccentricities and adjust the orbitalparameters so that the spacecraft form an equi-lateral triangle with nearly constant distances be-tween them. Then they find that to the first orderin the parameter l/2R, where l ∼ 5×106 km, is thedistance between two spacecraft and R = 1 A. U.∼ 1.5 × 108 km, the distances between spacecraftare exactly constant; any variation in arm-lengthsshould result from higher orders in l/2R or fromexternal perturbations of Jupiter and the seculareffect due to the Earth’s gravitational field. (Theeccentricity e is related in a simple way to the ratiol/2R.) In fact their analysis shows explicitly, thatsuch formations are possible with any number ofspacecraft provided they lie in a plane making anangle of 60 with the ecliptic. This general result isestablished with the help of the Hill’s or Clohessy-Wiltshire equations. Such analysis would be use-ful in order to carry out theoretical studies on theoptical links, simulators etc. However, the exact

orbits in the 60 plane give a maximum variationof armlengths of about 120,000 km. S. Koshti, R.Nayak and Dhurandhar have found that this max-imum variation in armlength can be reduced if thetilt angle of the orbit is slightly varied from the60 plane. This work is in progress. This observa-tion could have profound implications for the LISAmission.

The gravitational sky map

The stochastic background of gravitational wavesis a promising avenue for exploring astrophysics aswell as cosmology. In addition to a nearly isotropic

22

relic background from the early universe, stochas-tic backgrounds can arise in the confusion limit ofastrophysical sources. The strong anisotropy in theGW background of the latter would be an invalu-able discriminant between the underlying sources.

The detection and mapping of the anisotropyin stochastic GW background bears strong sem-blance to the analysis of the cosmic microwavebackground (CMB) anisotropy and polarizationwhich is also a stochastic field statistically de-scribed in terms of its correlation properties. S.Mitra, T. Souradeep and S. V. Dhurandhar will firstidentify the key features that would allow appropri-ate techniques from CMB analysis to be adapted toGW.

The raw sky map of the GW background is thesignal convolved with antennae pattern. The futureprogramme envisaged by the team is as follows:Various image reconstruction techniques for the ap-plication to the GW background will be exploredand compared. An efficient method to reconstructthe true sky map will be developed. Bayesianimage reconstruction techniques will be explored.The measured stochastic GW background wouldhave components arising from various astrophysi-cal sources. The spectral signature of the sourceswould allow separation of the components. Effi-cient methods related to optimal filters and theiranalysis will be developed.

Cosmology and Structure For-mation

Trans Planckian effects in inflation

In many of the models of inflation, the period ofacceleration lasts sufficiently long so that lengthscales that are of cosmological interest today wouldhave emerged from sub-Planckian length scales atthe beginning of inflation. This suggests thatphysics at the very high energy scales can, in prin-ciple, modify the primordial perturbation spectrumand these modifications can-in turn-leave their sig-natures on the CMB. This has led to a considerableinterest in understanding the effects of Planck scalephysics on the inflationary perturbation spectrumand the CMB.

Recently, T. Padmanabhan and L. Sriramku-mar have investigated this issue carefully and havenoticed that there is a new twist to this question.They begin by noticing that, in a Friedmann uni-verse, each mode qk of the scalar field, labeled bythe wave vector k, evolves as an independent os-cillator with time dependent parameters that arerelated to the expansion factor a(t). Given thequantum state ψk[qk, ti(k)] for the mode qk at an

initial time ti(k), one can obtain the state at alater time t by integrating over the (path integral)kernel K(qk, t; qk, ti) for an oscillator with timedependent parameters, which can be written downin terms of the classical solution.

To make any progress, we need to make an as-sumption regarding ψk[qk, ti(k)] and our results areonly as valid as this assumption. If we now furthermodify the dynamics (due to a phenomenologicalinput regarding trans-Planckian physics), we willbe changing the form of the kernel K. But, sincewe can only observe the integrated effect of K andψk[qk, ti(k)], the observations can tell us somethingabout the K (and trans-Planckian physics) onlyif we assume something about ψk[qk, ti(k)]. Theusual assumption is to consider the initial quantumstate to be the Bunch-Davies vacuum, but it is onlyan assumption. The crucial question is whether theeffects of trans-Planckian physics can be mimickedby a different choice of the initial state other thanthe Bunch-Davies vacuum.

Padmanabhan and Sriramkumar prove therather strong result that any (modified) spectrumof fluctuations can be reproduced from a suitablychosen squeezed state above the Bunch-Davies vac-uum in the standard theory. In fact, they go furtherand provide an explicit construction of the statefor any spectrum of the perturbations that is ob-served. So, if some specific deviation from the stan-dard scale invariant spectrum is seen in the CMB,a conservative interpretation will be to attributeit to a deviation from the standard initial state ofthe theory. Unless this possibility is ruled out, onecannot claim that the observation supports, say, aparticular model of trans-Planckian phenomenol-ogy. Motivated by this result, they argue that theCMB can at most help us identify the quantumstate of the scalar field in the standard theory, butit can not aid us in discriminating between the var-ious Planck scale models of the matter fields.

Quintessential inflation on the brane

One of the most remarkable discoveries of the pastdecade is that the universe is accelerating. Ev-idence for an accelerating universe comes fromobservations of high redshift type Ia supernovaetreated as standardized candles and, more indi-rectly, by observations of the cosmic microwavebackground and galaxy clustering. Perhaps thesimplest explanation for acceleration is the pres-ence of vacuum energy exhibiting itself as a smallcosmological constant with equation of state p =−ρ = constant. However, its un-evolving natureimplies that the cosmological constant must be setto an extremely small value in order to dominatethe expansion dynamics of the universe at precisely

23

the present epoch and this gives rise (according toone’s perspective) either to an initial ‘fine-tuning’problem or to a ‘cosmic coincidence’ problem. As aresult several radically different alternative meth-ods of generating ‘dark energy’ at a sufficiently latecosmological epoch have been suggested. V. Sahni,M. Sami and Y. Shtanov have focused on one suchapproach which rests on the notion that spacetimeis higher dimensional, and that our observable uni-verse is a (3+1)-dimensional ‘brane’ which is em-bedded in a (4+1)-dimensional ‘bulk’ spacetime.Higher dimensional braneworld models allow theexpansion dynamics to be radically different fromthat predicted by conventional Einstein gravity in3+1 dimensions. An important ‘surprise’ whichsprings from the braneworld models is that bothearly and late time acceleration can be successfullyunified within a single scheme in which the verysame scalar field which drives inflation at earlytimes becomes quintessence at late times.

Sahni and Sami have noted an intriguing issuein cosmology, namely that the universe appears toaccelerate twice: once at the very beginning dur-ing Inflation and again about 10 billion years later,during the present epoch. Although, most theo-retical models assume that there is no real con-nection between the two epochs and that infla-tion and dark energy are distinct physical entities,Sahni and Sami speculated that the two phenom-ena might, in fact, be related, and that the samescalar field which initially drives inflation, later,when its density has been considerably reduced,plays the role of quintessence. The main line of rea-soning behind this approach is simple and is basedon higher dimensional braneworld models based onthe Randall–Sundrum scenario. In the Randall–Sundrum model, the modified Einstein equationson the brane contain high-energy corrections as wellas the projection of the Weyl tensor from the bulkon to the brane. This results in the presence ofan additional quadratic density term in the Ein-stein equations. They have showed that this newterm substantially increases the damping experi-enced by a scalar field as it rolls down its potential.As a result, the class of potentials which lead to in-flation increases and includes potentials which arenormally too steep to be associated with inflationsuch as V (φ) ∝ φ−α, α ≥ 1.

Scalar fields with steep potentials (dubbed‘quintessence’) provide an attractive phenomeno-logical model for dark energy, since a large class ofinitial conditions can be funneled into a common‘tracker-like’ evolutionary trajectory at late times.Tracker models such as V (φ) ∝ φ−α significantlyameliorate the fine tuning problem faced by a cos-mological constant and have been used to describethe current evolution of the universe.

In an earlier work, Sahni, Sami and Souradeephad shown that although quintessential inflation isindeed possible to realise within the Braneworldscenario, such a model is generically accompaniedby gravitational radiation whose amplitude andspectrum are exceedingly sensitive to the details ofinflation and, particularly, on the mechanism of ‘re-heating’ the universe after inflation. Indeed, in or-der to ensure that the inflaton survives until todayone usually invokes a method of reheating basedon the quantum mechanical production of particlesin the time-varying gravitational field after infla-tion. This method of reheating is very inefficient,and leads to a ‘kinetic regime’ of prolonged du-ration when braneworld corrections are no longerimportant and the scalar field rapidly drops downa steep potential, resulting in pφ ' ρφ ' φ2/2 anda ∝ t1/3. Gravity waves, (see Fig. 1) created quan-tum mechanically during the kinetic regime havea ‘blue tilt’ and, for a prolonged kinetic regime,their energy density can dominate the energy den-sity of the universe and violate nucleosynthesis con-straints. Thus, conventional braneworld models ofquintessential inflation run into serious problemsassociated with copious graviton production whichrenders them unviable for an extended region inparameter space. Sahni and Sami have shown thatit is possible to circumvent this problem if, insteadof gravitational particle production, one invokes analternative method of reheating, namely ‘instantpreheating’ proposed by Felder, Kofman and Linde.This method results in a much higher reheat tem-perature and therefore, in a much shorter durationkinetic regime. (see Fig. 2). As a result, the ampli-tude of relic gravity waves is greatly reduced andthere is no longer any conflict with nucleosynthesisconstraints.

An important consequence of this unifiedmodel of inflation and dark energy is that once theinflationary regime is over and braneworld correc-tions cease to play an important role, the extremesteepness of the potential causes the scalar fieldto plunge down its potential resulting in a ‘kineticregime’ prior to reheating during which pφ ' ρφ.It is well known that the spectrum of relic grav-ity waves created quantum mechanically during in-flation is sensitive to and bears an imprint of thepost-inflationary equation of state. The effect ofthe kinetic regime is to create a ‘blue’ gravity wavespectrum on short wavelength scales, which is animportant observational signature of quintessentialinflation on the brane and could be tested by futuregravity wave experiments (see Figure 1).

24

(II) RESEARCH BY VIS-ITING ASSOCIATES AND

LONG TERM VISITORS

Gravitational Theory and

Gravitational Waves

Ahsan, Zafar

It is known that the Riemann curvature tensor canbe decomposed in terms of the Weyl conformal ten-sor, the Ricci tensor and the metric tensor. Thisdecomposition involves certain irreducible tensors.In empty space time, the pure gravitatinal radia-tion field is described by the Weyl conformal ten-sor. However, when gravitational waves propagatethrough matter, the Weyl tensor is still pertinent.In 1962, C. Lanczos thought that the Weyl tensorcan also be derivable from a simpler tensor field,and this can indeed be done through the covariantdifferentiation of a tensor field. This tensor field isnow known as Lanczos potential. In Godel geome-try, a two rank symmetric tensor which satisfies thewave equation and generates a Lanczos potentialhas been constructed by Zafar Ahsan in collabora-tion with J. H. Caltenco and J. L. Lopez-Bonilla ofMexico.

Using the Newman-Penrose formalism, a con-formally flat solution of Einstein-Maxwell equa-tions for null electromagnetic field has been ob-tained.

Banerjee, Asit

Recent Supernovae observations indicate an accel-erated expansion of the universe and lead to thesearch for a new type of energy, said to be the darkenergy, which violates the strong energy condition.The Chaplygin gas obeying an equation of state likep = −B/ρ−n provides such a model, which evolvesasymptotically to a cosmological constant modelwith accelerated expansion. Asit Banerjee alongwith his collaborators has found a model which, isvalid from the radiation era to Λ CDM stage andstudied its characteristics with the help of state-finder parameters.

Szekeres family of solutions for quasi-sphericalspacetime with dust has so far been generalized bymany workers to perfect and also imperfect fluidwith heat flow, fluid with cosmological constantand even to higher dimensions. Banerjee, and col-laborators have obtained a family of higher dimen-sional solutions in the scalar tensor theory of grav-itation. In fact, the Brans-Dicke field equationsexpressed in Dickes revised units are solved andexhaustively studied for all the subfamilies. A par-ticular group of solutions may also be interpreted

as due to the presence of the so called C-field ofHoyle and Narlikar with a choice of the couplingparameter.

Ghosh, Sushant

One of the most famous conjectures in general rela-tivity is the so called cosmic censorship conjecture,(CCC) which states that, for physically reason-able initial data, spacetime cannot evolve towardsa naked singularity, i.e., the spacetime singularityis always hidden inside black holes, indicating thata far away observer will not be influenced by it.Despite almost 30 years of effort, the CCC remainsas one of the most outstanding unresolved ques-tions in GR. It turns out that such a theorem isintractable due to complexity of the Einstein fieldequations.

S. Ghosh and A. K. Dawood have proved atheorem that characterizes a large family of non-static solutions to Einstein equations, representingin general, spherically symmetric Type II fluid. Itis shown that the best known dynamical black holesolutions to Einstein equations are particular casesfrom this family. The solutions found can be usefulto get insights into more general gravitational col-lapse situations and in general better understand-ing of CCC.

S. Ghosh and D. W. Deshkar in collaborationwith N. Dadhich have studied the spherically sym-metric collapse of a fluid with nonvanishing radialpressure in higher dimensional spacetime. They ob-tain the general exact solution in the closed formfor the equation of state (Pr = γρ), which leadsto the explicit construction of the root equationgoverning the nature (black hole versus naked sin-gularity) of the central singularity. A remarkablefeature of the root equation is its invariance for thecases; (D, γ = 0) and (D + 1, γ = −1) where D isthe dimension of spacetime. For the ultimate endresult of the collapse, these two cases are absolutelyequivalent, which is indeed a very interesting newresult that brings out the interplay between dimen-sion D of space∼Vtime and the equation of stateparameter γ.

Ghosh has investigated the occurrence ofnaked singularities in the gravitational collapse ofan inhomogeneous dust cloud in an expanding deSitter background - a piece of Tolman-Bondi de Sit-ter spacetime. It turns out that the collapse pro-ceed in the same way as in the Minkowski back-ground, i.e., the strong curvature naked singular-ities form and thus, violate the cosmic censorshipconjecture. His result unambiguously supports thefact that the asymptotic flatness of spacetime isnot a necessary ingredient for the development ofnaked singularities.

48

Ibohal, Ng.

By applying Newman-Janis algorithm to a spher-ically symmetric seed metric, Ibohal Ng. hasdiscussed general rotating metrics in terms ofNewman-Penrose (NP) quantities involving Wang-Wu functions. From these NP quantities, he derivesa class of rotating solutions including (i) Vaidya-Bonnor, (ii) Kerr-Newman-Vaidya, (iii) de Sitter,(iv) Kerr-Newman-Vaidya-de Sitter and (v) Kerr-Newman-monopole. The rotating Kerr-Newman-Vaidya solution represents a black hole that theKerr-Newman black hole is embedded into the ro-tating Vaidya radiating universe. In the case ofKerr-Newman-Vaidya-de Sitter solution, one candescribe it as the Kerr-Newman black hole is em-bedded into the rotating Vaidya-de Sitter universe,and similarly, Kerr-Newman-monopole. He hasalso discussed the physical properties by observ-ing the energy momentum tensors of these solu-tions. These embedded solutions can be expressedin Kerr-Schild forms describing the extensions ofGlass and Krisch superposition, which is furtherthe extension of Xanthopoulos superposition. It isshown that, by considering the charge to be a func-tion of radial coordinate, the Hawkings continuousradiation of black holes can be expressed in classicalspacetime metrics for these embedded black holes.It is also found that the electrical radiation willcontinue to form instantaneous charged black holesand creating embedded negative mass naked singu-larities describing the possible life style of radiatingembedded black holes during their continuous ra-diation processes. The surface gravity, entropy andangular velocity, are also presented for each of theembedded black holes.

In another paper, Ibohal Ng. and Dorendrohave derived a class of non-stationary rotating so-lutions including Vaidya-Bonnor-de Sitter, Vaidya-Bonnor-monopole and Vaidya-Bonnor-Kerr. Theserotating solutions describe embedded black holes.By considering the charge to be function of uand r, they discuss the Hawking’s evaporationof the masses of variable-charged non-embedded,non-rotating and rotating Vaidya-Bonnor, and em-

bedded rotating, Vaidya-Bonnor-de Sitter, Vaidya-Bonnor monopole and Vaidya-Bonnor-Kerr, blackholes. It is shown that every electrical radiation ofvariable-charged black holes will produce a changein the mass of the body without affecting theMaxwell scalar in non-embedded cases; whereas inembedded cases the Maxwell scalar, the cosmolog-ical constant, monopole charge and the Kerr massare not affected by the radiation. It is also foundthat during the Hawking’s radiation process, af-ter the complete evaporation of masses of thesevariable-charged black holes, the electrical radia-

tion will continue creating (i) negative mass nakedsingularities in non-embedded ones, and (ii) embed-ded negative mass naked singularities in embedded

black holes. The surface gravity, entropy and an-gular velocity of the horizon are presented for eachof these non-stationary black holes.

Kuriakose, V. C.

The discovery of emission of thermal radiation byblack holes led to the belief that a black hole canexist in thermal equilibrium with a heat bath pos-sessing a characteristic temperature distribution,otherwise the black hole would have evaporatedcompletely. Back reaction programme is foundto be useful in explaining the thermal equilibriumof black holes. P.I. Kuriakose and V.C. Kuri-akose have studied the back reaction effect for theSchwarzschild - anti de Sitter and Schwarzschild -de Sitter black holes and calculated the change inentropy due to back reaction effect. One of themost useful and efficient ways to study the prop-erties of black holes is scattering of matter wavesby black holes. This study is crucial to the un-derstanding of the signals expected to be receivedby the new generation of gravitational detectors.R. Sini and Kuriakose are now investigating thisproblem in detail.

Nandi, Kamal Kanti

One of the frontier areas of theoretical physics isthe topic of traversable Lorentzian wormholes. Ka-mal Kanti Nandi, along with collaborators, studiedstatic, spherically symmetric traversable wormholesolutions in the vacuum low energy string theoryand in general relativity. Two related topics of in-vestigation are: the constraints imposed on the sizeof the wormholes at semiclassical and quantum fieldtheoretic level and the proposal of a volume quan-tifier for exotic matter. They are presently engagedin calculating the entropy of quantum fields in thebackground of brane world black holes.

Patil, K. D.

Today, a well known and challenging open problemin general relativity is the cosmic censorship con-jecture(CCC). The higher dimensional theory hasopened up new and exciting direction of research inquantum gravity. Hence, to prove or disprove CCC,it becomes necessary to study the gravitational col-lapse in the higher dimensions as well. K. D. Patiland R. V. Saraykar have studied necessary condi-tions for the occurrence of naked singularities in thehigher dimensional dust collapse. They have ana-lyzed the higher dimensional non-marginally boundinhomogeneous dust collapse, where the initial data

49

consist of finitely differentiable functions of comov-ing coordinaters. It has been shown that as thedimensions of the spacetime increase, the calcula-tions of the derivatives of both, density as well asvelocity distribution functions of less orders nearthe centre, are required to decide the nature of thesingularity.

Pradhan, Anirudh

The occurrence of magnetic fields on galactic scaleis a well-established fact today and their impor-tance for a variety of astrophysical phenomena isgenerally acknowledged. E. R. Horrison has sug-gested that magnetic field could have a cosmologi-cal origin. As a natural consequence, one includesmagnetic fields in the energy momentum tensor ofthe early universe. Anisotropic magnetic field mod-els have significant contribution in the evolution ofgalaxies and stellar objects. In this context, a de-tailed study of relevant theories has been under-taken by A. Pradhan and S.K. Singh, consideringan anisotropic homogeneous Bianchi type I metric.

The general dynamics of tilted models havebeen studied by A. R. King and G. F. R. Ellis. El-lis and J. E. Baldwin have shown that we are likelyto be living in a tilted universe and they have indi-cated how we may detect it. Spacetimes of Bianchitype I, V and IX universes are the generalizationof FRW models and they would be interesting toconstruct cosmological models of types which areof class one. A. Pradhan and Abha Rai have stud-ied tilted Bianchi type V cosmological models fieldwith disordered radiation in presence of a bulk vis-cous fluid and heat flow.

Several modifications of Einstein’s general rel-ativity have been proposed and studied extensivelyso far by many cosmologists to unify gravitationand many other effects in the universe. Barber hasproduced two continuous self creation theories bymodifying the Brans-Dicke theory and general rel-ativity. The modified theories create the universeout of self-contained gravitational and matter field.However, the solution of the one-body problems re-veal unsatisfactory characteristics of the first the-ory and in particular the principle of equivalence isviolated severely. The second theory retains the at-tractive features of the first theory and overcomesdemerits thereof. The second one is an adaptationof general relativity to include continuous creationand is within the observational ambit. In view ofthe consistency of Barbers second theory of gravi-tation, A. Pradhan and H.R. Pandey have studiedsome of the aspects of this theory and investigatedLRS Bianchi type I cosmological model in Barberssecond theory of gravitation.

Ray, Saibal

Experimental result regarding the maximum limitof the radius of the electron (∼ 10−16cm) and a fewof the theoretical works suggest that there mightbe some negative energy density regions within theparticle in the general relativity. As a continuationof the studies on “Electromagnetic Mass” models,where gravitational mass of an electron originatesfrom the electromagnetic field alone, S. Ray and S.Bhadra have argued that such a negative energydensity also can be obtained with a better physicalinterpretation in the framework of Einstein-Cartantheory.

S. Ray has also studied the history of elec-tromagnetic mass models and hence, search a cluefor unification of electromagnetic and gravitationalfields after describing the status of mass in relativ-ity theory and quantum mechanics.

Saraykar, R. V.

Gravitational collapse of type I matter fields start-ing from regular initial data comprising of contin-uously differentiable mass functions and velocitydistributions results into either a black hole or anaked singularity (one that is visible to a far awayobserver) depending on the choice of initial data.The interesting question is whether the occurrenceof naked singularities is stable under small changesin the initial data, and whether this occurrence isgeneric? R. V. Saraykar and Sanjay B. Sarwe haveinvestigated this and proved that the occurrence ofnaked singularities is stable under small changes inthe initial data, small changes being in the appro-priate functional analytic sense. They also provedthat though the initial data leading to both blackholes and naked singularities form a big subset ofthe initial data set, their occurrence is not generic.The word generic is appropriately defined follow-ing the theory of dynamical systems. Furthermore,they illustrated the particular case of radial pres-sure to get clear picture of how a naked singularityis formed and how it is stable with respect to initialdata.

Saraykar, in collaboration with Sarwe, has alsostudied gravitational collapse of five dimensionalspherically symmetric self - similar perfect fluidspacetime with adiabatic equation of state, consid-ering all families of future directed non-space likegeodesics. They have proved that the spacetimeadmits globally strong curvature naked singulari-ties in the sense of Tipler and thus, violates cosmiccensorship conjecture. For this, weak energy con-dition is necessary, so that the singularity is visiblefor a finite period of time. Moreover, the solution ismatched to five dimensional Schwarzschild solution

50

using junction conditions.In another paper, Saraykar, along with K.

D. Patil, investigated higher dimensional non-marginally bound inhomogeneous dust collapse,where initial data consists of finitely differentiablefunctions of comoving coordinate. They haveproved that with the introduction of a velocity dis-tribution function, the results on the occurrence ofa naked singularity get slightly modified in com-parison with the marginally bound collapse. Theyhave also discussed the nature of families of radialnull geodesics emanating from the singularity.

Causal structure of spacetime has been stud-ied by many researchers working in classical gen-eral relativity and it has been successfully appliedby Hawking, Penrose, Geroch et. al. in provingsingularity theorems. In 1996, Sorkin and Wool-gar defined the concept of K- causality, which ismore general than usual concept of causality. Re-cently, in 2003, Garcia - Parrado and Senovilla in-troduced the concept of causal maps and studiedcausal structure of spacetime with a new perspec-tive. Causal maps are more general than confor-mal maps. Saraykar and Sujatha Janardhan, in arecent paper, combined these works to prove someresults in the K-causal, structure setting which aregeneralizations of results of Garcia- Parrado andSenovilla. They defined concepts like future sets,reflecting and distinguishing spacetimes etc. in K-causal setting, and proved that these propertiesare preserved under K-causal maps. Path-metricLorentz manifolds which satisfy K-causality condi-tion (which is stronger than strong causality) area special case of C0 - Lorentz manifolds and somemore properties can be proved for these spacetimes.They found that this approach is simpler and moregeneral as compared to traditional causal approach.

Sarmah, Bhim Prasad

Einstein’s general theory of relativity predicts theexistence of gravitational waves, propagating vir-tually unimpeded through spacetime at the vac-uum speed of light and carrying the imprints ofthe dynamics of the source. These are very weakwaves and quadrupolar in nature, i.e., a sourcehaving 2nd order time rate of change in asymmet-ric distribution of the mass/mass current can emitgravitational waves. Among the prospective astro-physical sources include the coalescence of binarycompact objects (Black Hole/Black Hole, BlackHole/Neutron Star, Neutron Star/Neutron Star),the supernova explosion, rapidly rotating and/oroscillating Neutron stars and CFS instabilities thatcan develop in fast rotating neutron stars, etc.

Bhim Prasad Sarmah is presently looking intothe gravitational waves generated from (1) r-mode

instability in neutron stars (2) core collapse super-nova with the help of simplified collapse model.Further, some calculations are being carried out toestimate the gravitational waves that can be emit-ted from the mini-creation event - the key com-ponent in the quasi-steady-state model of the uni-verse.

Singh, G. P.

Higher-dimensional view of the world geometrysuggests that the universe started in (4+D) dimen-sional phase with extra D dimensions either col-lapsing and stabilizing or remain at a size closeto the Plank length, while three others continuedto expand. The study of physics in higher dimen-sional spacetime has been stimulated by investi-gations of superstring and supergravity theories.A number of researchers have studied higher di-mensional spacetimes both in localized and cos-mological domains. In connection with localizedsources, higher dimensional generalizations of theSchwarzschild, Reissner-Nordstrom, Kerr-de Sitter,Tolman and Vaidya spacetimes have been studiedby several authors. G.P. Singh and S. Kotambkarhave studied charged fluid distribution on the back-ground of higher dimensional spheroidal spacetime.It has been observed that the new solution obtainedin their study, generates several known solutions forcompact star having spheroidal spacetime geome-try.

Classical and Quantum Cos-

mology

M. Sami

M. Sami and his collaborators, have been involvedin the investigations of models of steep braneworldinflation and observational constraints. It wasdemonstrated that steep brane world inflation canbe made consistent with WMAP observations ifGauss-Bonnet correction is invoked in the bulk.Part of activities were devoted to D-brane infla-tion and tachyon assisted inflation. A way to solvethe reheating problem in these models was pointedout in the recent work.

In context with dark energy, M. Sami has beeninvolved in the study of tachyon field models. In aseries of papers with collaborators, he has studiedthe general features of tachyon field if it is to besuitable to dark energy. His latest work focuseson the possibility of coupling of dark energy withmatter. Special emphasis in this work is given tothe role of scaling solutions in the scenarios of darkenergy. The study of observational constraints in

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these models is under active consideration.

Chaudhuri, Sarbeswar

In brane cosmology it is assumed that the stan-dard model particles are confined in a hypersurface,called the brane, embedded in a higher dimensionalspace called the bulk. Only gravity and other ex-otic matter such as dilaton can propagate in thebulk. Our universe may be such a brane like ob-ject. Randall and Sundrum [Phys. Rev. Lett. 83,3370 (1999); Phys. Rev. Lett. 83, 4690 (1999)]considered a model in which the brane is at a con-stant tension and the bulk spacetime has negativecosmological constant.

S. Chaudhuri, in collaboration with S.Chakraborty, is now engaged in generating so-lutions of gravitational field equations for ananisotropic brane with Bianchi type I universe withperfect fluid and scalar fields as matter sources hav-ing non-vanishing Weyl tensor of the bulk. Thepressure is assumed to bear a linear relation withthe matter density. It is shown that the inclusionof the energy term for non-vanishing Weyl tensorin the bulk, in the general gravitational field equa-tions is reflected in the final result by means ofan additive term in the parametric expressions ascompared to the works of Chen, et. al. [Phys. Rev.D64, 044013 (2001)]. By redefining the initial cos-mological time, it is shown that the brane cosmol-ogy evolves from a singular state with volume scalefactor equal to zero from time t=0. For a partic-ular non-zero value of the pressure but less thanthe matter density, the solutions are obtained inan exact analytic form with and without the cos-mological constant for a Bianchi type I universe.The expressions for the volume scale factor, ex-pansion scalar, deceleration parameter, shear andanisotropy are evaluated in both the cases.

Jain, Deepak

The nature of the dark components (dark mat-ter and dark energy) that dominate the currentcosmic evolution is a completely open question atpresent. Motivated by recent developments in par-ticle physics and cosmology, there has been growinginterest in a unified description of dark matter anddark energy scenarios.

Deepak Jain along with Abha Dev, and Jail-son S. Alcaniz, has investigated the predictions ofone of the candidates for a unified scenario for darkmatter/energy, the so-called generalized Chaply-gin gas using the CLASS lensing sample and su-pernova data. The generalized Chaplygin gas isparametrized by an equation of state p = −A/ρα,where A and α are arbitrary constants. It is shown

that, although the model is in good agreement withthis radio sample, the limits obtained from CLASSstatistics are only marginally compatible with theones obtained from other cosmological tests.

Jain, Dev and S. Mahajan have used CLASSstatistical sample to constrain the properties ofdark energy described by an equation of state(w = P/ρ). They exploit observed image sepa-rations of the multiply-imaged lensed radio sourcesin the sample. They use two different tests: (1) im-age separation distribution function n(∆θ) of thelensed radio sources and (2) ∆θpred vs ∆θobs asobservational tools to constrain the cosmologicalparameters w and Ωm. The results are in concor-dance with the bounds imposed by other cosmolog-ical tests.

John, Moncy V.

Using a significantly improved version of a model-independent, cosmographic approach, Moncy V.John has attempted to address an important ques-tion relevant to cosmology: Was there a deceler-ating past for the universe? To answer this, theBayes’s probability theory was employed, whichis the most appropriate tool for quantifying ourknowledge when it changes through the acquisi-tion of new data. The cosmographic approachhelps to sort out the models in which the uni-verse was always accelerating from those in whichit decelerated for at least some time in the pe-riod of interest. Bayesian model comparison tech-nique is used to discriminate these rival hypothe-ses with the aid of recent releases of supernovadata. He also attempts to provide and improve an-other example of Bayesian model comparison, per-formed between some Friedmann models, using thesame data. The conclusion was that the apparentmagnitude-redshift data alone cannot discriminatethese competing hypotheses. It was argued that thelessons learnt using Bayesian theory are extremelyvaluable to avoid frequent U-turns in cosmology.

Pradhan, Anirudh and Jotania, Kanti

In recent times, the cosmological constant (Λ) hasinterested theoretician and observers for variousreasons. The non-trivial role of vacuum in the earlyuniverse generates a Λ-term that leads to inflation-ary phase. Observationally, this term provides anadditional parameter to accommodate conflictingdata on the values of Hubble constant (H0), thedeceleration parameter (q), density parameter(Ω)and the age of the universe. The Λ owes its originto vacuum interactions. It follows that it would bein general, a function of space and time coordinatesrather than be static constant.

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A. Pradhan, P. K. Singh and Kanti Jotaniahave considered symmetric non-static cosmologi-cal models representing a bulk viscous fluid distri-bution, which are inhomogeneous and anisotropic.They obtain a cosmological constant as a decreas-ing function of time (without assuming any ‘ad hoc’

law). In this study, they have focused upon estab-lishing a formalism for studying the general rela-tivistic evolution in presence of bulk viscous in anexpanding universe. It is well known that in anearly stage of the universe when the radiation inthe form of photon as well as neutrino decoupledfrom matter, it behaved like a viscous fluid. Theviscosity coefficient of bulk viscous fluid is assumedto be power law function of mass density.

In their detailed study, they have found twoviable models by fixing reasonably well boundaryconditions on metric potential, namely, m, a andk with equation of state p = γρ (0 < γ ≤ 1, withmoderate value of γ = 0.5). The values of cosmo-logical “constant” Λ for these models are found tobe small and positive. Strong point of these models,is that it incorporates the matter density naturallyand so makes feasible, which can incorporate thephysical constraints. These models needs furtherstudy to include some mechanism of Λ with eithermatter or radiation.

Pandey, Sanjay K.

Probing large scale structure of the universe at highredshifts by studying redshifted 1420 MHz emis-sion from neutral hydrogen (HI) at early epoch hasbeen an interesting recent trend. Sanjay Pandeyhas used this to probe non-Gaussianity in HI distri-bution at the epoch of reionization of the universe.The HI distribution at the epoch of reionization(EOR) is largely determined by the sizes and dis-tribution of the ionized regions. In the scenariowhere the ionized regions have comoving sizes ofthe order of a few Mpc, the large scale statisticalproperties of the HI distribution are dominated bythe Poisson noise of the discrete ionized regions,and it is highly non-Gaussian. He has investigatedthe possibility of probing reionization by studyingthese non-Gaussian features using future radio in-terferometric observations of redshifted 21 cm HIradiation. He has developed a formalism relat-ing correlations between the visibilities measuredat three different baselines and frequencies to thebispectrum of HI fluctuations. For visibilities atthe same frequency, this signal is found to be of thesame order as the two visibility correlation whichprobes the HI power spectrum. For visibilities atdifferent frequencies, we find that the correlationsdecay within a frequency difference of ∼ 1 MHz.This implies that it is, in principle, straightfor-

ward to extract this HI signal from various con-taminants, which are believed to have a continuumspectra and are expected to be correlated even atlarge frequency separations.

Another problem, he has been interested in, issynthesis of deuterium in the incipient Pop II stars.Deuterium is regarded as an ideal “baryometer” fordetermining baryon content of the universe. Sitesfor incipient low metallicity (Pop II) star formationcan support environments conducive to Deuteriumproduction up to levels observed in the universe.This could have a deep impact on Standard Cos-mology.

He has also investigated a case of nucleosyn-thesis in slowly evolving models. He presents acase for cosmological nucleosynthesis in an FRWuniverse, in which the scale factor expands lin-early with time. It is demonstrated that adequateamount of baryon density that saturates massbounds from galactic clusters is required. There is acollateral metallicity production that is quite closeto the lowest metallicity observed in metal poorPop II stars and clouds. On the other hand, sitesfor incipient low metallicity (Pop II) star formationcan support environments conducive to deuteriumproduction up to levels observed in the universe. Aprofile of a revised “Standard Cosmology” is out-lined.

Ray, Saibal

Einstein equations have been solved by S. Rayand U. Mukhopadhyay for some specific dynami-cal models of the cosmological term Λ. Connectingthe free parameters of the models with the cosmicmatter and vacuum-energy density parameters, itis shown that the models are equivalent. Using theselected models, present values of some of the phys-ical parameters have been estimated and a glimpseof the past decelerating universe has also been pre-sented. Most of these nicely agree with the valuesas suggested by the Type Ia Supernovae data.

It has also been shown by them that the es-timates of different cosmological parameters fromthe model under perfect fluid distribution with astiff equation of state ρ = p are in good agreementwith the experimental results, especially 13.79 Gyras the age of the universe is quite satisfactory.

Seshadri, T.R.

Anisotropy in the Cosmic Microwave BackgroundRadiation arising from vector type (rotational) ve-locity fields (induced by primordial magnetic fields)in models with homogeneous re-ionization havebeen computed by T. R. Seshadri and K. Subrama-nian. It has been shown that re-ionization leads to

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an additional anisotropy of about 0.3 to 0.4 µK forsmall angular scales corresponding to l ∼ 10, 000.Transition to homogeneity in the SDSS slices havebeen investigated. It is shown that the distribu-tion of galaxies on scales of 80 h−1Mpc and aboveis homogeneous and the transition from fractal be-haviour to the homogeneity is somewhere around60 h−1Mpc. It is further shown that the distribu-tion of galaxies is similar to that in ΛCDM model ofbias 1.6. This work was done with Jaswant Yadav,Somanth Bharadwaj and Biswajeet Pandey.

Scalar fields whose energy density grows expo-nentially with scale factor have been investigated.It has been shown by T. R. Seshadri and S. Unnikr-ishnan that these can be candidates of dark energy.It has further been shown that in certain cases, thescalar filed is a phantom field. Bounds on parame-ters of such fields from the observations of the latetime accelerated phase of the universe have beenstudied.

Chakraborty, Subenoy

Quasi-spherical spacetime in higher dimension hasbeen studied by Subenoy Chakraborty and co-workers. S. Chakraborty and U. Debnath havefound cosmological solutions in arbitrary spacetimedimension of Szekers model with perfect fluid asthe matter content and have examined the asymp-totic behaviour of these solutions. Cosmologicalsolutions in Brans-Dicke theory for higher dimen-sional Szekers model have been obtained by S.Chakraborty, U. Debnath and A. Banerjee, andthey have obtained C-field cosmology in a particu-lar case.

A detailed study of gravitational collapse inhigher dimensional Szekers spacetime has been in-vestigated by S. Chakraborty and U. Debnath.They have determined conditions for naked sin-gularity in different physical situations, both formarginally and non-marginally bound cases. Also,they have examined null geodesics for global visi-bility of naked singularity.

In studying quintessence problem, S.Chakraborty in collaboration with A. Baner-jee and U. Debnath has examined the role ofmodified chaplygin gas for accelerating universe.They have shown that the model can describe theuniverse from radiation to Λ CDM era.

Variable gravitational constant and cosmologi-cal constant have been studied in anisotropic branecosmology by S. Chakraboty, U. Debnath and S.Nath. They have presented the solutions for var-ious cases and compared their results with ob-servations. Lastly, string - dust cosmology inbrane world scenario have been discussed by S.Chakraborty, A. K. De and S. Bhanja.

Paul, B. C.

In recent years, there are interesting developmentsthat led to the study in string inspired cosmology.Particularly, in higher dimensional scenario, ourobserved universe may be described by a brane em-bedded in higher dimensional spacetime with theusual matter field and force confined on the brane.The gravitational field may propagate through thebulk dimensions perpendicular to the brane. Onecan accommodate a large number of dimensionswith extra space. While discussing the applicationsof brane worlds, one often assumes Einstein grav-ity in the bulk and then projects the dynamics onthe brane. This leads to the high energy correc-tions in the Friedmann equation which changes inthe expansion dynamics of the early universe. B.C. Paul and A. Beesham have shown that in thebrane world, the anisotropic universe approachesthe isotropic phase via inflation much faster thanin GTR. They have noted a case where the curva-ture term initially drives power law inflation on theisotropic brane which is, however, not permitted inGTR. All Bianchi models except Bianchi type IX,transit to an inflationary regime and B. C. Pauland A. M. Sami have studied the tachyonic infla-tion in brane with Gauss-Bonnet term in the bulk.They have obtained exact solution of slow roll equa-tions in the case of an exponential potential. Theyattempt to implement the proposal of Lidsey andNunes [Phys. Rev. D 67, 103510 (2003)] for thetachyon condensate rolling on the Gauss-Bonnetbrane.

Galaxies and Quasars

Chatterjee, Tanuka

To investigate the formation process of galaxies amodel has been developed using Cluster AnalysisTechnique to the globular clusters in M31, LMCand our galaxy to find the optimum number of clus-ters in these systems. In every case, they exhibitmulti-population structure instead of bimodalitywith respect to colour as have been found in manygiant elliptical galaxies and spiral galaxies. It alsoincreases the importance of inclusion of many pa-rameters and at the same time eliminating redun-dant parameters and helps to enunciate a modifiedtheory of globular cluster formation of the youngextragalactic as well as old GCs with respect tomore than a single parameter at a time to find theoptimum number of clusters. This is unlike themethod of drawing histograms, which only can con-sider one parameter at a time, and unsuitable fora multivariate set up. These histograms show bi-modality with respect to colour in bright elliptical

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galaxies while cluster analysis shows multimodal-ity.

Jog, Chanda

N-body simulations of mergers of galaxies in thenew regime of unequal-mass galaxies with the massratio 4:1-10:1 have been studied by Chanda Jog.The study uses a powerful FFT code and a millionparticles per galaxy and includes the effects of gas,thus, the study treats realistic systems. It is shownthat such mergers result in very peculiar, mixedsystems that have the morphology of a spiral galaxybut have kinematics similar to an elliptical galaxy(see Bournaud, Combes, and Jog 2004 for details).It is argued that such mergers are more likely tooccur than the equal-mass mergers studied so farin the literature, and will affect the dynamics andevolution of galaxies.

A theoretical model for gravitationally coupledstars and gas in a galactic disk embedded in a darkmatter halo is developed. The observed verticaldistribution of the atomic hydrogen gas in the outergalaxy is used to constrain the parameters of thedark matter halo. The best fit is given by a spheri-cal halo with a density profile that falls faster thanthe usual isothermal halo. This has important im-plications for the size and mass of the galaxy (fordetails see Narayan, Saha, and Jog 2005).

Khare, Pushpa

Pushpa Khare along with her collaborators ob-tained the metal abundances in 4 Damped Ly-man Alpha systems (DLAs) with redshift smallerthan 0.6, using the Hubble Space Telescope. Theycombined these measurements with their earliermeasurements taken with Multiple Mirror Tele-scope (MMT) at Arizona and other abundancemeasurements reported in the literature to deter-mine the rate of chemical evolution in the universe.The global mean metallicity seems to increase onlyweakly with decreasing redshift and does not seemto rise to solar abundance even at z' 0. She alongwith her collaborators observed seven low redshiftDLAs in the spectra of QSOs in May 2004 andFebruary 2005, with the MMT with the aim of de-termining the metal abundances in these systems.They have also been awarded 3 nights at the VeryLarge Telescope at Chile for observations of DLAs.She continued to be involved in the preparation of acatalogue of absorption lines in the spectra of QSOsobserved by the Sloan Digital Sky Survey (SDSS)as an official member of the SDSS collaborationworking on QSO absorption lines.

Pandey, S. K.

With the objective of establishing evidence for themultiphase (hot, warm and ionized, cool molec-ular gas and dust) ISM in elliptical galaxies, awell defined sample of elliptical galaxies was chosenfor carrying out observations in optical, infraredas well as in X-ray bands. A subsample of ninegalaxies was observed in near-infrared (NIR)-JHK-bands using 3.5m NTT and near-IR camera SOFIat the European Southern Observatory (ESO) dur-ing December 2002. Ellipse fitting procedure wasused to derive the surface brightness, ellipticity, po-sition angle profiles as well as higher order Fouriercoefficients. The unsharp masking technique wasthen applied to the galaxy images in the Ks-bandto look for substructures in them. This led to de-tection of a spiral structure in the core of the galaxyNGC 1553 (figure 21). This is the first time suchsubstructure has been unveiled from near IR bandimages of early-type galaxies. Detailed analysis isin progress. Three observing nights has been allot-ted to this observing programme on NTT/SOFI atESO during May-June 2005 for carrying out near-IR JHKs observations of a set of 20 galaxies. Theseobservations will be the first of its kind for a welldefined large sample, and will lead to a detailed un-derstanding of the nature, origin and evolution ofISM in elliptical galaxies. People involved in thisjoint collaborative programme include A. K Kem-bhavi, S. Raychaudhaury, and Sudhanshu Barway.

As a part of an ongoing programme on study-ing properties of dust in early-type galaxies, deepimages in BVRI and H-alpha of about 25 galax-ies were obtained during the period 2004-05 usingthe 2m HCT of IIA. Data reduction and analysisis in progress. Results on NGC3801 a S0/a galaxywith rather complex dust features was reported atthe XXIII meeting of ASI held at ARIES, Nainital.D. K. Sahu, M K Patil, S. Barway, Rabin Chhetriand Laxmikant Chaware are also involved in thisproject.

Pandey, U. S.

An interesting work on self-gravitating gaseousdisks has concerned the behaviour of the precur-sor of the massive central dark object that mightbe energy source existing at the centre of galax-ies and powering quasars. With this view, U. S.Pandey has presented a model of self-gravitatinggas flattened in a disk.

He makes the following assumptions: (i) theinteraction force between individual pairs of parti-cles is negligibly small, (ii) the distribution functionf in phase space satisfies collision-free Boltzmannequation, and (iii) the system is conservative. They

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Figure 21: A mosaic of various observations of the elliptical galaxy NGC1553. The optical image in themiddle was used by Malin to show the presence of shells in this galaxy. The Chandra X-ray to the left showsspiral structure in the hot gas, as does the H-alpha image in the bottom right. Unsharp-masked near-IR Ksimage on the top right taken with NTT/SOFI shows spiral structure in the core, on a smaller scale and notaligned with the structure in the hot gas.

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set up a third order differential equation satisfiedby the dusk for the asymmetric cases. They obtaina particular solution for the disk in steady state.

It has been suggested by him that a nuclearactivity at the centres of galaxies might be dueto instabilities in the self-gravitating gaseous disks.Active galactic nuclei might involve subsequentlythrough LINER starburst - centre nuclear burningphases. The surface mass density σ and core tem-perature are two parameters which may decipherthe evolution of AGNs.

The work on perturbation of self gravitatinggaseous disk is being done jointly by U. S. Pandeyand Sanjeev Kumar Tiwari.

They discuss the stability of a thin, self-gravitating gaseous disk flattened (in a plane)around the nucleus of a galaxy. The instability cri-terion demands that it would be sensitive to starformation provided surface mass density is largerthan a critical value. They derive the expressionfor wavelength of critical perturbation. They findthat critical Toomre wavelength is larger than theradius of a disk for typical Jeans disk. Using sim-ple analysis, they show that an uniformly rotatingcollision-less disk with finite temperature will beunstable via gravitational radial perturbation forpractically all wavelengths.

Patil, M. K.

Traditionally, early type galaxies were believed tobe the inert systems, mostly composed of popu-lation II type stars, essentially devoid of gas anddust, and virtually a total absence of on-going starformation process, barring few exceptions. How-ever, this scenario has changed drastically over lasttwo decades due to the excellent observing facilitiesthroughout the electromagnetic spectrum and theuse of powerful imaging devices in astronomy. DeepCCD imaging of early-type galaxies and their care-ful analysis has revealed that a significant fractionof the early-type galaxies do harbour the multi-phase ISM. Though origin of multiphase ISM inearly-type galaxies is controversial subject at themoment, a detailed study of morphologies of dustand other phases of ISM in these galaxies alongwith their environment lead one to assess the va-lidity of various theoretical models that have beenproposed for the secular evolution of ISM in theearly-type galaxies.

M. K. Patil, in collaboration with S. K.Pandey, Ajit Kembhavi, U. C. Joshi and D. K. Sahuhas carried out a detailed surface photometric anal-ysis of a sample of early-type galaxies in the near-IR as well as optical pass bands, with the objectiveof deriving the extinction properties of dust in ex-tragalactic environment and comparing those with

dust in the Milky Way. Extinction curves derivedfor majority of galaxies run parallel to the canonicalcurve of the Milky Way, indicating similar dust ex-tinction properties in external galaxies. However,the RV values derived for these galaxies were foundto vary as a function of the dust morphology aswell as the environment of the host galaxy, in thesense that the galaxies in the dense region showlarger RV value compared to those in the isolatedregions. Estimates of dust masses from optical ex-tinction were found to be an order of magnitudeless than those derived from IRAS flux densities,implying that a large fraction of dust distributedthroughout the galaxy remained unattended in theoptical method.

They have also made an attempt to explore thephysical association of the multi-phase ISM (hotgas, warm gas, and dust) in early type galaxies byanalyzing broad band CCD images as well as X-ray images from the Chandra X-ray observatory.The morphologies of optical emission line (Hα im-ages) are found to be strikingly similar with thoseof the dust morphologies as well as the hot gasmorphologies (diffuse X-ray emission maps), im-plying a strong association of all the three phasesof ISM. They found a strong correlation betweenthe dust and cool as well as warm gas, however, amarginal anti-correlation was observed between thedust content and the X-ray flux, in the sense thatgalaxies with large scale dust features exhibit lowerX-ray flux. Further, the X-ray spectra extractedfrom the analysis of the high-resolution X-ray im-ages shows the signatures of OVIII and FeXVIIIemission lines, showing the metal enrichment na-ture of the hot gas.

Compact Objects and X-ray Bi-naries

Chandra, Deepak

Deepak Chandra, Meenu Dahiya and Ashok Goyalhave continued their study of the phase structureof the Nambu-Jona-Lasinio model. They are exam-ining the parameters of compact hybrid stars usingthe NJL model for the quark EOS.

Deepak Chandra, along with Ashok Goyal hasstudied quark gluon plasma formed in heavy ioncollisions. They have found that the interactionsin QGP and the hadron gas reduce the delay inthe phase transition, but the curvature energy hasa mixed behavior. Lower values of surface tensionincrease supercooling in contrast to that in earlyuniverse studies. Higher values of bag pressure tendto speed up the transition.

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Paul, B. C.

B. C. Paul has obtained a class of relativistic so-lutions of compact stars in hydrostatic equilibriumconsidering it embedded in a higher dimensionalspacetime. The spacetime geometry is assumed tobe a (D - 1)-spheroid immersed in a D-dimensionalEuclidean space. Here, he obtains a solution ofthe field equation which is a generalisation of theMukherjee, Paul and Dadhich [Class. Quantum

Grav. 14, 3475 (1997)] solution in higher dimen-sions. It is noted that the spheroidal parameterplays here a very important role in determining theequation of state of a very compact cold star. Itis observed that the higher dimensional spacetimecan accommodate a more massive compact objectfor a given size compared to that in the usual fourdimensional spacetimes.

Tikekar, Ramesh and Jotania, Kanti

The studies of the recently discovered stellar ob-jects such as X-ray pulsar Her X-1, X-ray Buster $U 1820-30, SAX tend to indicate that their physicalcontent is likely to be strange matter - quark matterand these objects seem to be strange stars or hybridneutron stars, which are likely to be formed duringcollapse of supernova cores. The usefulness of theVaidya-Tikekar ansatz, which effectively prescribesthe density variation in the spherical compact starsin equilibrium, assuming their content to be in theform of a perfect fluid, in the absence of definiteinformation about the nature of their content isknown to provide instructive models of such con-figurations. Two families of relativistic models ofspherical compact stars have been proposed basedon two classes of general solutions of relativisticequations characterized by three parameters, fol-lowing the Vaidya-Tikekar approach of prescribingthe geometry of the interior 3-space of the config-uration. The set up is shown to provide physi-cally viable models of compact spherical stars ifthe compactification parameter, density variationparameter and the surface density of the matterfor the configuration are known. The EOS of theinterior matter of the models is seen to get approx-imated to linear form in this set up. The causalbahaviour, adiabatic aspects and stability againstradial pulsations of the models are being examined.The set up is also found to accommodate modelsof compact spherical stellar stars with anisotropicpressures. The models of such super dense stars,in the general set up provided by the three param-eter families of solutions of relativistic equations,are being studied following the core-envelope ap-proach which prescribes that the interior of the starcomprises of two regions, a core containing fluid

with anisotropic pressure surrounded by an enve-lope filled with a perfect fluid. The work is beingpursued by Ramesh Tikekar and Kanti Jotania.

Dey, Jishnu

Careful assessment of four good superburst eventsfor GX 17+1 reveals that a superburst is possibleat near Eddington mass accretion rates. JishnuDey in collaboration with Monika Sinha, Mira Deyand Subharthi Ray has given an alternative sce-nario for superburst, i.e., that they originate froma strange star’s surface, which is a micron-thicklayer of diquarks. The diquarks break up due to re-peated Type 1 bursts during high accretion like anavalanche, due to the two-fermion to boson trans-formation. After this, the reverse process takesover. The crucial fact is that the recombinationtime scale is long, since the strong interaction pair-ing process is supplemented by beta equilibriumand charge neutralization which are slower thanweak electromagnetic processes.

Four experimental groups reporting on rela-tivistic heavy ion collisions (RHIC), with gold ongold, show that quark gluon plasma with asymp-totic freedom and chiral symmetry restoration(CSR) may never be realized in RHIC althougha non-hadronic phase is reached. Manjari Bagchi,Jishnu Dey and collaborators calculated strangestar properties using large Nc approximation withbuilt-in CSR where they performed a relativisticHartree-Fock calculation, using Richardson poten-tial as an interquark interaction. This potentialhas the asymptotic freedom and a confinement-deconfinement mechanism built into it. In theircalculation, they employed two scale parameters Λand Λ′. The linear confinement string tension fromlattice calculations is 350 MeV and the Coulomb -like part has the parameter 100 MeV from deep in-elastic scattering experiments. They also took theeffect of temperature (T) on gluon mass in a sim-ple way, following Alexanian and Nair in additionto the usual density dependence and found that thetransition T from hadronic matter to strange mat-ter is 80 MeV, close to the 100 MeV estimated byWitten in 1984.

It appears that there is a genuine shortage ofradio pulsars with surface magnetic fields signifi-cantly smaller than ∼ 108 Gauss. It has alreadybeen established that pulsars with low magneticfields are the products of x-ray binaries where theyundergo accretion-induced field decay. In these bi-naries the neutron stars are also likely to undergoan accretion-induced deconfinement transition andconvert into strange stars. J. Dey, in collaborationwith R. Ray Mandal S. Konar, M. Sinha and M.Dey calculated the Landau-Ginzburg free energy of

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a rotating strange star and found that a particu-lar value of the magnetic field would minimize thefree energy. For a suitable set of QCD parame-ters this value is ∼ 107 Gauss. They proposed thatthe pulsars with very low magnetic fields are actu-ally strange stars locked in a state of minimum freeenergy and therefore at a limiting value of the mag-netic field which can not be lowered by the systemspontaneously.

Dey, Mira

The study of different aspects of strange quarkmatter and its formation of compact quark staris continued. The surface vibrations of strangestars are related with observational emission spec-trum from six compact stars which are believed tobe strange star candidates. In the previous work,the equation of state (EOS) of strange quark mat-ter was derived with phenomenological Richardsonpotential with same asymptotic and confinementscale. Since these two scales are different, in prin-ciple, Richardson potential was modified and it wastested for hadron properties like ∆++ and Ω− mag-netic moments (with latest experimental numbers)and their masses. With these two different scalesthe new EOS is derived and further work is inprogress.

Shanthi, K.

Neutron star X -ray binaries exhibit a wide rangeof timing phenomena, which can be quantified bycomputing the Fourier transform of the observedlight curve. The power density spectra (which arethe amplitude squared of the Fourier transforms)often exhibit Gaussian like features at certain fre-quencies, which are called Quasi Periodic Oscilla-tions (QPO).

RXTE observations of the atoll source 4U 1636- 53 over the last five years were analysed by K.Shanthi and R. Misra and an automated search forkHz QPO was done. The fraction f of the time thesystem exhibits a kHz QPO decreases from nearunity for the lowest flux state (∼ 1400c/s) to zerofor the highest (> 2550c/s). The variation of fre-quency with count rates has revealed three distinctparallel tracks which are coincident with the threeflux states.

In continuation of this work they are systemat-ically studying the spectra of this source at differ-ent flux levels and also when the QPO is present orabsent, which will throw light on the origin of thephenomena and the nature of these systems. Datafrom another low mass X-ray binary, 4U 1608-52is being analysed to ascertain the generality of theresults obtained earlier.

Stars and Interstellar Medium

Das, M. K. and Saha, L. M.

Based on Principal Component Analysis (PCA) amathematical framework has been developed by M.K. Das and Manabu Yuasa (RIST, Kinki Univer-sity, Japan) to analyze the effect of missing data.This method can be used in the spectral classifi-cation of stars. It happens frequently that the ob-servational data is not complete but missing partlyby various reasons. IRAS 3 colours of mass-losingstars and their expanding velocity on the groundbased observations were used as an experiment andthe adjusted values were restored using the formal-ism developed. The original data and restored onesare compared and the distribution of the restorederrors have been studied by Das and L. M. Saha.

Pandey, S. K.

Continuing the work on photometric monitoringof chromospherically active stars, S. K. Pandeyand Sudhanshu Barway have obtained the multi-wavelength (BVRI) photometry of two active stars,namely, HD52452 one of the shortest period non-eclipsing binary star, and a newly identified RSCVn binary star HD61396, was analysed and re-sults were published. Detailed investigation of thelong-term photometric variations in an active late-type giant FK Com (HD 11755), a prototype of theFK Comae group of active stars, which are rapidlyrotating, single, late-type giants with strong chro-mospheric and transition region emission, has beencarried out. The V band light curves collected frompreviously published photometric observations dur-ing the period 1966-2003 were modeled in the framework of standard star-spot model. Activity cy-cles were searched in the star using various activ-ity tracers such as minimum, maximum and meanmagnitude, amplitude, integrated magnitude andtotal spot area. The analysis reveals presence oftwo dominant types of spot activity cycles; one haslong period of 28 years and another with short pe-riod of 6 years. The long period correspond to thetime scale of variations in the total spottedness,while the short period corresponds to the cycle of“flip-flops” behaviour, in which the dominant partof the spot activity shifts 180 degrees in longitudeover a short period of time and remains at this newactive longitude for some time.

Low-resolution spectroscopic observations of asample of newly identified as well as suspected chro-mospherically active stars were also carried out us-ing HCT 2m telescope at Hanle during the year2004-2005 for seven nights. The spectra were takenin H- alpha region using HFOSC instrument. Allthe stars except HD 61396 show the absorption in

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H-alpha. The star HD 61396 was found to exhibitthe emission in H-alpha. Detailed investigation isin progress.

Singh, H. P.

Harinder P. Singh in collaboration with RanjanGupta (IUCAA) and their counterparts, JamesRose (UNC, Chapel Hill), Frank Valdes and DaveBell (NOAO, Tucson) have just completed a ma-jor task of creating a database of spectra of 1273stars. The spectrum of a star gives astronomers theinformation about the chemical composition andphysical nature. They used the 0.9 m Coude-FieldTelescope at the Kitt Peak National Observatoryin Arizona, USA and it took about 7 years forthem to complete the painstaking work. This mam-moth work was supported by an INDO-US projectfunded by Department of Science and Technology,New Delhi, India and National Science Foundation,Washington, USA. The data is available online onthe web at www.noao.edu/cflib and is also pub-lished in the Astrophysical Journal.

In collaboration with R. Gupta, K. Volkand S. Kwok (Calgary), an artificial neural net-work scheme was employed to classify 2000 brightsources from the IRAS low resolution spectraldatabase. A classification accuracy of more than80 percent was achieved. The scheme will be uti-lized to classify another 8000 sources in the IRASdatabase.

A stellar spectral library in the near infraredis being built in collaboration with A. Ranade (Vi-gyan Prasar), N.M. Ashok (PRL) and R Gupta.The first release containing reduced H-band spec-tra is available at the Virtual Observatory Indiawebsite: www.iucaa.ernet.in/ voi

Chandra, Suresh

Suresh Chandra and his group is working on asym-metric top molecules of astronomical interest. Re-cently, they have suggested that the molecule C5H2

may be identified in cosmic objects through itstransition 313−404 at 4.3 GHz in absorption againstthe cosmic microwave background. Further, forthe molecule and Si2C, they found that it may beidentified in cosmic objects through its transitions414−505, 515−606, 212−303, 313−404, and 111−202

at 15.9, 5.1, 33.6, 24.9, and 42.3 GHz in absorptionagainst the cosmic microwave background, in a re-gion having low temperature.

Depending on the relative orientations of nu-clear spins of two hydrogen atoms, the hydrogenmolecule (H2) has two species: para (I=0, anti-parallel spins) and ortho (I=1, parallel spins). Theratio of the population N1 of ortho-H2 in J = 1

level to the population N0 of para-H2 in J = 0level are quite often related through the standardBoltzmann factor. Chandra has written a commenton this relation.

Indulekha, K.

K. Indulekha along with K. Ambili has worked onthe puzzle of bound open clusters. The feasibility ofstar -gas, dynamical friction, and interactions withlow mass stars as mechanisms which would leadto the formation of open clusters was investigated.The analysis, applied to observational data, led tothe conclusion that high and low mass clusters haddifferent histories of formation. K. Indulekha andA. Cherian are investigating using a toy model, theimportance of random distributions of sensors inthe case of human and insect eyes as well as in thecase of adaptive optics. The localization of neu-trinos in dense stellar matter, and its impact onstellar evolution is being investigated along withG. V. Vijayagovindan and S. Sreedevi.

Rastogi, Shantanu

IR emission fhas eatures at 3050, 1610, 1310, 1165and 885 cm−1 (3.28, 6.2, 7.7, 8.6 and 11.2 µm)correspond to the emissions from Polycyclic Aro-matic Hydrocarbon (PAH) molecules are knownas Aromatic Infrared bands (AIBs). The AIBsare ubiquitous in a variety of interstellar regions,viz. planetary nebulae, proto-planetary nebulae,reflection nebulae, H II regions and even in ex-tra galactic sources. These IR features seem tobe a result of emissions from a family of PAHsconsisting of neutrals, cations, anions and hydro-genated/dehydrogenated molecules. Observationsshow source to source variations in the IR bandsrelated to the type of PAHs present in the sur-rounding medium. To get a better understand-ing of the interstellar spectra, spectral variationswith shape, size and ionization state of PAHs havebeen studied by Amit Pathak and Shantanu Ras-togi. A systematic study of several PAHs and theircations has been done using ab-initio density func-tional method. The variation in intensity of IRbands upon ionization is related to the change incharge distribution within the molecules. The C-Hstretch intensity increases as the partial charge onthe hydrogen atoms in the PAH decrease. Theo-retical IR spectra for catacondensed and pericon-densed PAHs in both neutral and ionic forms showthat large compact PAH cations are prefered in theISM. Study of very large PAHs is also underwayusing the High Performance Computing facility atIUCAA.

PAHs are also believed to contribute to

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the overall UV interstellar extinction hump at217.5 nm and are thought to be carriers of someof the Diffuse Interstellar Bands (DIBs) (a numberof absorption features superposed on the interstel-lar extinction curve) observed in the visible andnear infrared spectral ranges. Ab-initio calculationof electronic transitions from PAH cations shall besimulated for comparison with DIBs.

Sun and the Solar System

Badruddin

Badruddin and his coworkers have carried out adetailed analysis of the time lags and hysteresiseffects of cosmic rays intensity and solar activityindices (Sunspot number, 10.7 cm radio flux andSolar flare index). They have utilized the neutronmonitor data and solar data extending over a pe-riod of 50 years covering five solar activity cycles(19-23). Polarity state of the heliosphere changesafter every 11 years. They have carried out theiranalysis during alternating polarity states of theheliosphere and studied the effect of polarity rever-sal on the motion of galactic cosmic rays in the 3-Dheliosphere.

Adopting the superposed epoch analysismethod, they have also studied the temporal varia-tion of cosmic ray intensity during the course of car-rington rotation periods in low solar activity con-ditions when transient eruptions from the sun arealmost absent. They have calculated average os-cillations in the cosmic ray intensity during differ-ent solar magnetic conditions. Regression analysisbetween intensity oscillation and tilt of the helio-spheric current sheet has also been carried out bythem.

Narain, Udit

U. Narain and his coworkers are working on mech-anisms responsible for maintaining the million de-gree hot solar and stellar coronae. At present theyare investigating the heating of solar and stellarcoronae by nano-/micro-flares, which is one of themost likely agents to heat the solar and stellarcoronae. Here, two oppositely directed magneticfieldlines come closer, and closer which increasesthe current density to large values. A small resis-tivity of corona increases dissipation considerably.This process is called magnetic reconnection. Suchevents take place throughout the corona and thusheating takes place. Here, magnetic energy is con-verted to thermal energy, which is spread to otherregions by thermal conduction.

Prasad, Lalan

Several mechanisms have been suggested to con-tribute the heating of solar corona. Generally,each model predicts to deposits energy along so-lar coronal loops in a characteristic way. S. Chan-dra and Lalan Prasad have studied the tempera-ture structure in a loop by expressing the magneticfield and fluid velocity in terms of ChandrasekharKendall functions. One of the most outstandingquestions in solar physics concerns the heating ofsolar corona. Since it was realized that the sunis surrounded by a million degree hot plasma, nu-merous ideas for its heating have been put forward.The solar magnetic field plays a leading role in bothtransporting the required energy up from the pho-tosphere and releasing it in the solar corona.

In connection with the problem, an analyticalmethod for the heating of solar coronal loops byphase-mixing process is discussed by using Alfvenwaves. Under typical coronal heating condition byohmic dissipation, phase-mixing can provide mag-netic energy on a time scale comparable with thecoronal radiative time. Under the assumption oflarge Lundquist numbers, the phase-mixing can at-tain a hot coronal loops. They introduce two mod-els of loop (1) half symmetric loop model and (2)cylindrical symmetric loop model. The magneticfield assumed to be static and associated with onlyin inhomogeneities plasma density. The solutionunder initial boundary condition and the ohmic dis-sipation have been discussed.

The concept of coronal heating by nanoflareare shown to the characteristics of active regionswhich results presumably from a large number ofmore or less random heating agents. The flares as-sociated with impulsive agents of magnetic energydissipation from 5 × 1024 to 1026 ergs, are callednanoflares. The analysis of these agents are repre-sented by a power law distribution as a function oftheir energies with a magnetic slop of 1.5. LalanPrasad and collaborators consider coronal heatingby nanoflare in the lower energy population of abroad spectrum of flare like events. An adjacentgroup of nanoflares are responsible for coronal heat-ing in terms of heating agents.

Sahijpal, Sandeep

S. Sahijpal has been investigating several aspectsrelated to the formation and the early evolutionof the solar system. Based on the recent X-raysflare observations of low-mass protostars made byChandra X-rays satellite, he has developed detailednumerical simulations that deal with the thermalprocessing and irradiation of Ca-Al-rich inclusions(CAIs, the earliest condensed solar system grains)

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in magnetic reconnection ring. The magnetic re-connection ring results from the interaction of cir-cumstellar accretion disc with the protosun’s mag-netosphere. Observed X-rays flare luminosities oflow-mass protostars in the Orion molecular cloudwere used to model various flare characteristics.This work has been attempted for the first time.Approximations were made regarding the thermalevolution that involves condensation, evaporationand coagulation of CAIs. Over two dozens of sim-ulations were run in order to explore the diver-sity and complexity of the irradiation environmentprevailing in the magnetic reconnection ring. En-sembles of refractory cores with ferromagnesiummantles were evolved for production of short-livednuclides, 7,10Be, 41Ca, 53Mn, 26Al, 36Cl, by ir-radiation. Around 30 proton, 3,4He induced nu-clear reactions were considered for the productionof the short-lived nuclides. Production rates ofthe short-lived nuclides were found to have wide-ranging spreads of at least two orders of magni-tude with no canonical value inferred for their ini-tial abundances in the early solar system. Super-flares corresponding to X-rays luminosities ≥ 1033

ergs/s. that could result in widespread evaporationof CAIs and thorough mixing of the inventories ofshort-lived nuclides would be essential to homog-enize the inferred spreads and explain the initialabundances of the short-lived nuclei in the earlysolar system.

Sahijpal has also initiated numerical model-ing of the accretion and planetary differentiationof asteroids in the early solar system. Based ondetailed studies of meteorites, there is ample evi-dence that some asteroids underwent moderate tosevere thermal processing in the early solar system.In certain cases, this resulted in large scale melt-ing and planetary differentiation of asteroids intoiron-cores with rocky-mantles thereby, suggestingthat planetary differentiation of terrestrial planetsinitiated at planetesimal stage. On the basis ofdetailed numerical simulations involving linear ac-cretional growth and planetary differentiation of as-teroids with the short-lived nuclides, 26Al and 60Fe,as the heat source, Sahijpal has found that in orderto have significant silicate melting, the onset of as-teroid accretion and formation of iron-core shouldoccur within ∼ 1.5 and ∼ 0.5 million years, re-spectively, from the time of condensation of CAIs.The developed thermal models numerically simu-late sinking of iron-melts towards the centre andupward flow of silicate melt towards the surface ofasteroids in a realistic manner. This is for the firsttime that the gradual movement of iron and sili-cate melts has been parametrically studied to un-derstand the dynamics of the flows and the timescales involved in planetary differentiation.

Sen, Asoke K.

After the last apparition of comet Halley in 1985-86, a number of other comets were observed in po-larimetry with IHW-continuum filters. From thein-situ dust measurements of Halley, dust size dis-tribution functions were obtained (Lamy et al.,1987; Mazets et al., 1986), which were later usedby several authors to interpret polarization dataof Halley. In a recent work done by A. K. Sen,polarimetric data of various comets have been an-alyzed, using Mie theory and assuming that thecomposition of dust particles does not differ fromcomet to comet (Delsemme 1987). The individ-ual grain size distribution functions so obtained forvarious comets suggest different values for relativeabundance of coarser grains. Introducing a ‘rela-tive abundance of coarser grains’ index g, one maystudy any possible dependence of g on the dynam-ical age of a comet, where the dynamical age canbe defined in terms of some of the orbital parame-ters of the comet. For the four non periodic cometsavailable for an analysis, he finds a clear empiricalrelation g = −2.5.q2/3 emerging out. This relationstrengthens the concept that comets whose grainsare processed more by the solar radiation (thesecomets may be dynamically older) do contain rela-tively lower number of finer grains.

Atmospheric and IonosphericPhysics

Reddy, R. Ramakrishna

The experimental potential energy curves for theelectronic ground states of molecules like CO+, CHand CH+ observed in comets are constructed byR. Ramakrishna Reddy and collaborators by us-ing the Rydberg-Klein-Rees method as modified byVanderslice, et al. The ground state dissociationenergies are determined by curve fitting techniqueusing the five parameter Hulburt - Hirschfelder (H-H) function. The estimated dissociation energiesare 8.33± 0.19, 3.48± 0.903 and 3.89± 0.102eV forCO+, CH and CH+ respectively. These valuesare in good agreement with the literature values.Estimated dissociation energies of CO+, CH andCH+ are used in the relation given by Gaydon andionization potentials are evaluated for CO and CHmolecules. The estimated ionization potential are14.03 and 10.85 eV respectively for CO and CH .The Franck-Condon factors and r-centroids for theband system of A 2Π - X 2Σ+ of CO+ moleculehave been calculated employing an approximateanalytical methods of Jarmain and Fraser. Theabsence of the bands in this system is explained.

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Plasma Physics

Khan, Manoranjan

Secondary electron emission from a charged dustgrain is a new mechanism identified for chargingmechanism in a complex plasma. This is equiva-lent to the flow of a positive current to the dustsurface and the secondary electron yield dependson the nature of the dust material and the kineticenergy of the incident electrons. The effect of sec-ondary electron emission on Dust Acoustic Wave(DAW) propagation has been studied by Manoran-jan Khan, in collaboration with M.R. Gupta, S.Sarkar, B. Roy, and A. Karmakar, based on orbitmotion limited theory of dust grain charging. Inthis three component plasma, the effect of ion andelectron capture and ionization of neutral atomsand recombination have been included. It is shownthat if the dust charge is positive, there may occurzero frequency exponentially growing perturbationabout the equilibrium characteristics.

DAW has been studied in a complex plasma fornon-thermal ions. In collaboration with S. Ghosh,M.R. Gupta and R. Bharuthram of West VilleUniversity (Durban, South Africa) instabilities ofDAW has been investigated by M. Khan.

In the area of instrumentation science, bio-logical samples are studied by Atomic Force Mi-croscopy (AFM) and Lateral Force Microscopy(LFM) images, in collaboration with K. Bhat-tacharyya, T. Guha, R. Bhar, V. Ganeshan, andR. L. Bhramachary. AFM, LFM images of human,avian, reptilian, amphibian and piscine erythocytesare examined to determine the general pattern oferythorocyte membrane architecture.

Kumar, Nagendra

The behaviour of nonlinear Alfven waves with smalland finite amplitude in an ideal viscous plasma hasbeen investigated by Nagendra Kumar in collabo-ration with H. Sikka. They consider a viscous andcompressible plasma in which the perturbations arerestricted along z axis only. Since the perturba-tion is caused by a low frequency small amplitudeAlfven wave propagating along z axis, this allows usto consider the dependence of the perturbation onz and t only. Using derivative expansion method,a nonlinear Schrodinger (NLS) equation describingthe nonlinear evolution of Alfven waves is obtained.It is concluded that a dispersive term appears inthe nonlinear Schrodinger wave equation only dueto viscosity and does not appear when we do nottake viscosity into account. Thus, in the absenceof viscosity higher order dispersive effects are re-quired to contain nonlinear growth of the wave. It

is suggested that our results would be useful in so-lar atmosphere and interstellar space, for example,Alfven waves propagating in solar corona, and stel-lar winds driven by Alfven waves. Partially ion-ized dusty plasmas are of great importance in thecontext of study of planetary magnetosphere, neb-ulas and comet tails. The study of instabilitiesin these partially dusty plasmas has drawn con-siderable interest in recent past particularly in fil-amentary structures of molecular clouds and den-sity condensation in accretion disks. Nagendra Ku-mar in collaboration with Vinod Kumar studiedthe fluid dynamical instabilities in magnetized par-tially ionized dense dusty plasma. They consider amagnetized partially ionized dense dusty plasmaswith dynamics governed by dust and neutral gascomponents. The dynamics of dusty plasma arecharacterized by collective behaviour for parame-ter regime of ordering a << e << ed, where a,d and ed are the dust grain radius, the averageintergrain distance and the plasma Debye length.The electron dynamics is not considered as the elec-trons have no significant influence on the overall be-haviour of dusty plasma. The plasma is consideredquasi-neutral. The homogeneous magnetic field istaken along the z-axis and the homogeneous grav-itational field is taken as g = −gey. They considerinterface along the z-axis, i.e., along the magneticfield and relative flow between dust and neutral gas.An instability condition is obtained and discussed.They follow the Hurwitz criterion and constructthe test sequence to obtain the condition for in-stability from the third Hurwitz sub-determinant.It is also interesting to note that stabilization oc-curs for modes with kz=0 due to dust -neutral gascollisions. The results might be useful in many sit-uations of astrophysical magnetized dusty plasmasnamely, comets and circumstellar dusty disks, e.g.,T-Tauri stars.

Mondal, K. K.

The linear and nonlinear properties of various dustassociated electrostatic waves (DA, DIA, DL waves,etc.) in dusty plasmas have been intensively inves-tigated and reported in a large number of regularand review articles or books during last few years.

In recent times, there has also been muchinterest in different novel electromagnetic eigen-modes in magnetized plasmas contaminated withmassive charged dust grains. A number of inves-tigations have been made on low frequency dust-electromagnetic waves propagating parallel andperpendicular to the ambient field direction. Theseare based on linear theories, which are true for thesmall-amplitude waves. However, there are numer-ous processes through which unstable modes can

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saturate and attain large amplitudes. For the large-amplitude waves, one should take into consider-ation nonlinearities, because they lead to varioustypes of interesting nonlinear coherent structureviz. solitons, shocks, vortices, etc.

Verheest (1995), Mamun (1999), and Shuklaand Verheest (2003) have investigated the non-linear propagation of low frequency electromag-netic Alfven waves (propagating along the ambientfield direction) in a magnetized multispecies dustyplasma and have discussed the properties of en-velope solitons. Meuris and Verheest (1996) havederived the K-dV equation for the weakly nonlin-ear propagation of dust magnetosonic waves propa-gating perpendicular to the ambient magnetic fielddirection. Mamun, et al. (2003) have developed acomplete theory (including linear, weakly nonlinearand fully nonlinear) for the oblique propagation ofhydromagnetic waves in a magnetized dusty plasmacontaining negatively charged dust grains and pos-itively charged ions.

Mondal, et al. have made a detailed linearanalysis of the hydromagnetic waves in a dust-ionplasma with the consideration of charge fluctuationof the dust grains. They have derived a dispersionrelation and analyzed it numerically to study vari-ous modes of wave propagation and instabilities ofthe waves.

Dynamics

Ambika, G. and Harikrishnan, K. P.

G. Ambika has studied numerically the phe-nomenon of Stochastic Resonance (SR) in a dy-namical system modeling a Josephson junction, to-gether with K. P. Harikrishnan. This system hasthe novel feature that it can function both as abistable set up and a threshold set up for realiz-ing SR. However, as a bistable set up for compos-ite but weak signals or signals of multiple frequen-cies, it detects only individual frequencies while asa threshold system with a proper resetting mecha-nism it detects the difference frequencies also. Inboth cases, the system is dynamically in an underdamped state.

The occurrence of SR in a Coupled Map Lat-tices (CML) with a bimodal cubic map as onsitedynamics is studied in detail in the temporal iter-ates of the central site as well as in the spatial it-erates for a frozen patterns at different times. Theanalysis is done for different coupling strengths andsystem size, so as to arrive at optimum conditions.The spatial SR has the welcome feature that theSignal to Noise Ratio (SNR) remains unchangedover a range of noise strengths.

The different dynamical states of a 2-dimensional recurrence relation called the Gu-mowski - Mira map is analysed to explain the widevariety of patterns it produces under iterations. Itis found that the patterns correspond to the in-termittency regions of the map and possible bifur-cation patterns are worked out. By coupling twosuch maps, the nature of synchronization and itscharacterization are being done. The stability of acrystal lattice that is harmonically coupled to itsneighbours but has a double well potential at eachlattice point is being analysed using a CML model.

In collaboration with A. K. Kembhavi, R.Misra and K. P. Harikrishnan, detailed nonlineartime series analysis of the X-ray data from the blackhole system GRS 1915+105 has been carried out byAmbika. Out of the 12 temporal states analyzed, 4clearly indicate low dimensional chaotic behaviour,while 3 shows stochastic nature. More over the pos-sibility of distinguishing chaos from coloured noiseis studied using the correlation dimension as themeasure and several realizations of the surrogatesof the data. This is being repeated with the Lya-punov exponent as the measure.

Das, M. K. and Saha, L. M.

M. K. Das and L. M. Saha have continued theirwork on nonlinear stability of motion in binarystar system within the frame work of restrictedthree-body problem. The effect of radiation pres-sure from binary components on the trajectoriesof a small mass element was investigated using themethod of nonlinear forcasting, as used in nonlineardynamics. Stability of motion has been also stud-ied using the Poincare surface of section. It hasbeen shown that the results of both the methodscompare well, but method of nonlinear forcasting ismuch simpler and provide insight into the details ofdynamics involved. Saha along with his students,and Das has worked in the area of nonlinear dy-namics and studied different systems using mapsand other tools.

Kuriakose, V. C.

Recently, much interest have been shown to studypulse propagation through realistic optical fibres.M. N. Vinoj and V. C. Kuriakose have studied pulsepropagation through dispersion decreasing fibresand found that high quality compressed ultrashortsoliton pulses free from pedestals pulses can be gen-erated when light propagates through a dispersiondecreasing fibres with fibre loss. Another area innonlinear optics where soliton finds applications isin photo refractive and photonic crystals. C. P.Jisha and Kuriakose have studied photo refractive

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solitons from the point of photonic switching appli-cations. P. D. Shaju and Kuriakose have proposeda simple method to create a double-well potential insemiannular Josephson junctions and obtained themethods for the manipulations of a vortex trappedin the junction. This finds applications in quantuminformation and quantum computing and Chitraand Kuriakose have started studying these aspects.

Mittal, A. K.

Seasonal mean rainfall anomalies are largely deter-mined by sea surface temperature anomalies. Inparticular, it is known that year-to-year variationof tropical Pacific sea surface temperature associ-ated with the El Nino/Southern Oscillations eventhave a strong influence on the inter-annual varia-tions in the monsoon. During the summer mon-soon season, the large-scale rainfall oscillates be-tween active spells with good rainfall and weakspells with little rainfall. Typically, the transitiontime between active and weak spells is shorter thanthe residence time of the spells themselves. Lorenzmodel is a widely used for predictability studies inmeteorology. Constant forcing terms have been in-troduced in the Lorenz model by Palmer to give aparadigmatic model for discussing long-range mon-soon predictability. The forcing terms in this modelrepresent the tropical Pacific sea surface tempera-ture anomaly. These terms cause a shift in theprobability distribution function between the twowings of the Lorenz butterfly, which represent theregimes of active and weak spells of the monsoon.

R. S. Yadav, S. Dwivedi and A. K. Mittal haveinvestigated rules for forecasting regime changesand their duration for this model. They have dis-covered simple regime change rules that make pre-dictions with near perfect accuracy. They havealso found similar regime prediction rules in someother two-regime attractors, suggesting operationof some universality mechanism. These rules canbe applied using observed data alone, without anyknowledge of the underlying dynamical system.They have shown how these rules can help predictintra-seasonal rainfall variability for a toy rainfallmodel. These results have led them to conjecturea positive correlation between magnitudes of max-imum anomaly during active rainfall spell and du-ration of subsequent break (dry) spell. Preliminaryanalysis of actual rainfall data appears to supportthe conjecture.

Hasan, S. N.

The research work done by S. N. Hasan involves thethree-body problem and galaxy dynamics. Appli-cation of Clifford Algebras to the problems of celes-

tial mechanics has been studied since a few years.It can be shown that this serves as a very powerfultool to the study problems in dynamics. Variousimportant theorems have been derived to demon-strate this and the Sun-Earth-Moon system stud-ied in this formulation. Dynamics of ejections fromstellar systems have been studied and a comparisonmade between ejecting and colliding systems in thelight of galaxy interaction. It was found that dis-ruptive effects are considerably less in the case ofejections if the ejected system is compact. Workhas also been started in an Indo-French projectwith Ajit Kembhavi in collaboration with BrunoGuiderdoni on GalICS. Preliminary results basedon the SQL database have been obtained.

Vishwakarma, J. P.

The imploding shock wave has been an attractivetopic in fluid dynamics, applied physics and en-gineering. In fact, imploding shock and detona-tion waves offer interesting possibilities of attain-ing extremely high temperature, pressure and den-sity. Also, the study of converging shocks in anon-uniform medium is applicable to the motionof shock waves in outer layer of a star, where thedensity goes to zero.

J. P. Vishwakarma, in collaboration with K.K. Singh considered the implosion of a cylindri-cal shock wave in a non-homogeneous ideal gas orin a homogeneous non-ideal gas in presence of anazimuthal magnetic field. The shock velocity andother flow variables just behind the shock are deter-mined by Whithams rule, in the cases, when (i) thegas is weakly ionized before and behind the shockfront, (ii) the gas is strongly ionized before andbehind the shock front, and (iii) the non-ionizedgas undergoes intense ionization as a result of thepassage of the shock. It is shown that the non-idealness of the gas, the variable density of theinitial medium and the presence of azimuthal mag-netic field have significant effects on the shock prop-agation.

J. P. Vishwakarma, in collaboration with S.Vishwakarma has obtained the similarity solutionsfor the region behind a converging cylindrical shockwave, where the flow is approximately isothermaldue to intense radiation heat transfer. The ini-tial density of the gas is assumed to be varyingas r−w, where r is the distance from the axis ofsymmetry and w, the inhomogeneity index. Therequirement of a single maximum pressure in theshocked-flow leads to an approximate determina-tion of self-similarity exponent for different valuesof w and γ, where γ is the ratio of specific heatsof the gas. It is shown that the above requirementis fulfilled only when the inhomogeneity index w

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satisfies the inequality 0.25 < w < 4/(γ + 1)2.

Theoretical Physics

Dutt, Ranabir

During last few years, Ranabir Dutt has showedthat the algebra of supersymmetry may be prof-itably applied to many non-relativistic quantummechanical problems. In supersymmetric quantummechanics (SUSYQM), one gets a better under-standing of why certain potentials are analyticallysolvable. All solvable potentials have the propertyof shape invariance, which is realized through a re-lationship between the two supersymmetric part-ner potentials with a change of parameters relatedby translation. When extended to WKB theory,SUSYQM - inspired WKB quantization conditions(SWKB) reveal several interesting features: Un-like the standard WKB method, the leading orderSWKB formula yields exact analytic expressionsfor the energy eigenvalues of all known shape invari-ant (SIP) potentials for which the change of param-eters are of translational type. For spherically sym-metric potentials, conventional Langer modifica-tion is not needed in the framework of SWKB the-ory. Furthermore, for non-exactly solvable cases,SWKB theory has so far predicted improved en-ergy eigenvalues from the leading order as well assub-leading orders as compared to those obtainedfrom the corresponding WKB calculations.

It may then be natural for one to examinewhether shape invariance and the exactness of theSWKB quantization formulae remain intact if thepotential under study is generalized to higher di-mensions. Dutt has studied the supersymmetricstructure of the two-dimensional quantum disk bil-liard, of which the one-dimensional version, theinfinite square-well potential, has been found tobe shape-invariant. He has shown that althoughthe shape invariance property is no longer valid intwo dimensions, SWKB predictions for the energyeigenvalues are more accurate than the correspond-ing ones obtained from the WKB calculations.

Dutt has examined also the SIPs from thestandpoint of periodic orbit theory. An exact traceformula for the quantum spectra of such potentialsis derived. On the basis of this finding, he has pre-sented a new derivation of the result that the lowestorder SWKB quantization rule is exact.

Gangal, Anil

Anil Gangal together with Abhay Parvate has es-tablished conjugacy of calculus on fractals and ordi-nary calculus. This conjugacy provides a practicaltool for solving fractal differential equations such

as fractal time relaxation equation, fractal diffusionequation, equation of motion of a particle involvingfriction in a fractal medium, etc.

Kaushal, R. S.

In recent years, in the studies of theories of earlyuniverse the coloured objects like quarks, diquarksand gluons are found to play an important role,particularly in the context of stability studies ofcertain stellar objects. R. S. Kaushal with A.K.Sisodiya and his other collaborators has been in-vestigating the role of multi-diquark interactionswithin the frame work of a polynomial field theory.In particular, using a generalized Pauli principleand the constituent quark model, the role of phi-4and phi-6 - terms in the effective Lagrangian writ-ten for scalar field phi, is investigated. In anotherrelated work, in collaboration with D. Parashar andA.K. Sisodiya, Kaushal has proposed a quark- dou-ble diquark model for the newly discovered pen-taquark baryons and tetraquark mesons as an ex-tension of his 27 year old work on the quark-diquarkmodel for the tri-quark baryons.

In several physical problems, particularly inthe studies of population biology, the role of non-linear terms in the diffusion equation has startedpenetrating in order to understand several newlydiscovered phenomena. Kaushal, in his recentwork, has advanced the solitary wave solutions toa certain types of nonlinear diffusion-reaction (D-R) equations in one dimension. The mathematicalcontents of the associated non-Hermitian Hamilto-nian with the linear counterpart of the D-R equa-tion are investigated in a great detail.

Malik, Usha

It has been suggested by Usha Malik and her col-laborators in an earlier publication that the high-Tc of a multi-component superconductor comesabout due to multiple phonon exchanges betweenthe electrons in it. So, the phonon propagator inthe Cooper problem has been replaced by a phononsuperpropagator. For this purpose, it is convenientto use Bethe-Salpeter formalism, because of theease with which it allows temperature to be in-troduced. The analysis also gives a satisfactoryexplanation of the observed fact that the Tc’s ofalloys are universally higher than that of their con-stituents.

As a follow up of the above approach in super-conductivity, the calculations of Tc’s of some of thebinary superconducting alloys are presented in thefollowing scenarios: (a) the alloy is characterizedby a single Debye temperature and (b) the alloy ischaracterized by two Debye temperatures.

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The same approach has been followed to in-terpret the size effects (in the nano particle range)observed experimentally in high Tc oxide super-conductors. The particle - size dependence of lat-tice constants plays a significant role in calculationsof Tc. This feature, along with increase in Debyetemperature and enhancement in electron densityof states at Fermi level on reduction in size appearsto have a strong hold on the Tc of multi componentsuperconductors.

Pandita, P. N.

The idea of grand unification is one of the mostcompelling theoretical ideas that goes beyond theStandard Model (SM). In grand unified theo-ries (GUT’s), the SM gauge group SU(3)×SU(2)×U(1) can be elegantly unified into a simple group.Moreover, the fermion content of the SM can be ac-commodated in irreducible representations of theunified gauge group. Also, one can understandthe smallness of neutrino masses via the seesawmechanism in some of the grand unified modelslike SO(10). Since, supersymmetry is at presentthe only known framework in which the Higgs sec-tor of the Standard Model is stable under radiativecorrections, one must consider grand unified theo-ries with underlying supersymmetry. In supersym-metric grand unified theories, the renormalizationgroup flow of the gauge couplings leads to theirunification at a very large scale.

P. N. Pandita, in collaboration with B. Anan-thanarayan, has carried out a detailed analysis ofthe sfermion mass spectrum that arises in SO(10)supersymmetric GUT. In supersymmetric SO(10)grand unification, the unified gauge group canbreak to the Standard Model gauge group throughdifferent chains. The breaking of SO(10) neces-sarily involves the reduction of the rank, and con-sequent generation of non-universal supersymme-try breaking scalar mass terms. By taking intoaccount these non-universal contributions to thesfermion masses, a set of squark and slepton massrelations has been derived, which can help distin-guish between the different chains through whichthe SO(10) gauge group breaks to the SM gaugegroup. Thus, these sum rules can serve as a cru-cial test of the symmetry breaking pattern of theSO(10) gauge group in the context of supersym-metric unification. The implications of these non-universal supersymmetry breaking scalar massesfor the low energy phenomenology have been stud-ied in detail.

Pandita, in collaboration with Katri Huitu,Jaari Laamanen and Sourov Roy, has carried outdetailed investigations of lightest neutralino (a pos-sible dark matter candidate) properties as well as

an upper bound on its mass in a supersymmetricGUT based on SU(5) gauge group. Such a grandunified theory can lead to non-universal gauginomasses at the unification scale. The phenomeno-logical implications of these non-universal gauginomasses arising from a grand unified theory in thecontext of the Large Hadron Collider have beenstudied in detail.

Ramesh, Babu T.

The cross sections for two and three-photon ioniza-tion of hydrogen atom is evaluated by T. RameshBabu by performing the infinite summations overthe complete set of atomic states including thecontinuum using the Dalgarno-Lewis metnod. Us-ing this method, a convenient analytical expres-sion is derived for Kramers-Heisenberg matrix el-ement, describing the elastic scattering of photonsby hydrogen atom. An analytical expression for thesecond-order AC Stark shift of the ground state ofatomic hydrogen is also derived.

Verma, R. C.

The Standard Model of elementary particle andtheir interactions has been quite successful in ex-plaining the electromagnetic and weak interactionsin leptonic and semileptonic sector. However,hadronic processes have posed serious challenges tothe model. Particularly, weak hadronic decay pro-cesses experience interference due to the less un-derstood strong interactions. Quantum chromody-namics provides a reliable description of the stronginteractions at high energy scale, but hadronizationof quarks to form the hadron bound states intro-duces serious complications. Experimentally, nowgood amount of data exist for the weak hadronicdecays involving s-wave hadrons. Consequently,theoretical efforts have been focused on charm andbottom hadrons emitting s-wave particles. How-ever, these hadrons being heavy can also emit p-wave hadrons. Recently, these decays have alsobeen observed experimentally, therefore, their the-oretical investigations acquire significance.

Now more precise measurements of hyperonmagnetic moments have become available, butthere exist serious discrepancies between experi-mental and theoretical predictions. R. C. Vermahas shown that a good agreement can be obtainedfor hyperon moments exploiting the concepts of ef-fective quark mass and effective quark charge in-side the baryons. He has first determined theeffective quark masses from the charmed baryonmasses by including spin-spin interaction causedby the exchange of gluons among the constituentquarks. Using the effective quark masses, he has

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calculated the moments by sandwiching the mag-netic moment operator between charmed baryonflavour-spin wave functions. Similarly, he has alsoinvestigated quark charge screening effects on thecharmed magnetic moments. The obtained valuesare expected to be tested in near future as seriousefforts are underway to measure charmed baryonmoments.

Theoretical progress on p-wave emitting weakdecays of heavy hadrons has been rather slow. Ini-tially, it was expected that these decays would besuppressed in comparison to the s-wave counter-parts. However, the available experimental infor-mation on such decays of charmed meson, thoughmeager, has already started showing discrepancywith such naive expectations. Since, charm andbottom hadrons are very heavy, they can decaythrough numerous channels emitting scalar and ax-ial vector mesons, which Verma has studied. Us-ing the QCD modified weak Hamiltonian based onthe Standard Model, he has studied weak non-leptonic decays of bottom mesons emitting pseu-doscalar and axial vector mesons using the factor-ization scheme, and calculated their branching ra-tios in Cabibbo favoured, Cabibbo suppressed, andCabibbo doubly suppressed modes. He has also in-vestigated two-body weak decays of charm baryonsemitting JP =+ baryons and scalar mesons usingthe factorization scheme, and made first estimatesfor their decay rates, and it is hoped that these re-sults would be helpful to experimentalists in theirmeasurements.

Cluster Computing for Ma-chine Learning

Ninan Sajeeth Philip

Santhom Cluster Project is a holistic approach toteaching and learning, in that the major emphasisis to the three aspects of learning, viz. (a) acqui-sition of Knowledge, (b) acquisition of Skill and(c) acquisition of Values. A survey in Technopark,the silicon valley in Kerala revealed that only 3 %of the students who pass out from the colleges inKerala acquire the skill level required by the in-dustries functioning there. While the state of Ker-ala is said to be hundred percent literate, this lowlevel of “hit rate” indicate some serious drawbackin the teaching and learning methodology adoptedby the educational institutions in the state. San-thom Cluster Project is an experiment to identifytalented students and to give them training in themissing aspects of learning with the aid of moderneducational tools, led by N. Sajeeth Philip.

The test of the concept was the six node cluster

building project done by five students and SajeethPhilip at St. Thomas College in 2003. An ex-tension of the project with 16 nodes was carriedout at IUCAA in April 2004 by the same group.Both these projects were completely student ori-ented, in the sense that each member in the teamfelt their involvement in the project and recognisedtheir contributions, whereby they gained self con-fidence and personal skill that supplemented theirtextual knowledge.

In October 2004, IUCAA donated 22 usedcomputers, with special sanction from UGC forthe cluster project at St. Thomas College. Thesemachines were used in two phases of the SanthomCluster Project. The first phase completed in De-cember 2004. About twenty B.Sc. final year stu-dents actively participated in the first phase ofthe project. Starting from preparing the room bypainting and wiring, they built the network and in-stalled OS on the machines. The facility built bythem is being used outside the working hours ofthe college by all interested students in the depart-ment to learn programing languages such as C andC++, in addition to other utilities and projects. Awide collection of self learning tutorials are madeavailable on these machines, so that students mayexplore themselves the topics of their choice with-out waiting for classroom lecture hours. Evalua-tion procedures showed remarkable improvement inlearning curves, ability to retain and recollect top-ics learned in the new environment as compared toconventional classroom learning.

The second phase of the Santhom ClusterProject started in January 2005 and is expectingcompletion by the end of March 2005. Six M.Sc.students, four from St. Thomas College and twofrom a nearby college work on this project. Theaim is to develop OS support for low memory andlow bandwidth clusters for massively parallel com-puting. A twelve node cluster is built with 10 Pen-tium 1 processors and two Celeron 2 GHz proces-sors under this project. The Pentium 1 machinesrun at about 300MHz clock speeds with a memoryof 32 MB, while the Celeron machines have 128MB RAM each. None of the machines boots fromlocal media; however, it is possible to have localhard disks for swap memory or provide local stor-age. Here again, every part of the project from as-sembling the machines, making network cables andclustering were all done by the students. The groupwas also able to modify the linux 2.4.27 vanilla ker-nel to run on as low as 16 MB RAM that now serveas the cluster OS on these systems. OpenMosix andLAM-MPI are installed on the cluster. Further op-timisation of the code and benchmarking are beingcarried out. The facility is built following the GNUculture of the Free Software Foundation and efforts

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are made to document the entire project so thatthose who wish to experiment similar setups maycopy them freely instead of reinventing the wheel.

Instrumentation

Dodia, Umesh

The CCD camera designed at IUCAA, compatibleto SBIG ST-6 commercial camera, has been repli-cated at IUCAA by Umesh Dodia under UGC Mi-nor research project, which will be very useful asa backend instrument to Bhavnagar University isAutomated Photoelectric Telescope (APT ) withthe two stage stay at IUCAA. This has includedmaking of CCD controller card, data grabber card,connection cables, related mechanical work, test-ing of controller with CCD head, familiarisation ofsoftwares CCDOPS and AIP4WIN by taking im-ages with CCD camera, construction of Low LevelLight Sourse (L3S) for advanced testing of CCDcamera, and Astronomical Image Processing forWindows (AIP4WIN). The results show that cam-era designed at IUCAA is a good instrument whichcan be produced at low cost about Rs. 30,000/-,which is possible under small projects like UGCminor research project.

No observational work could be carried out dueto some logistic problems regarding Observatory.(It has taken about 2 years to shift the Observatorydome, which was damaged due to earthquake to thedepartment building.)

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(III) IUCAA-NCRAGRADUATE SCHOOL

Two IUCAA Research Scholars, ParampreetSingh (Guide: N.K. Dadhich) and TirthankarRoy Choudhury (Guide: T. Padmanabhan)have defended their theses submitted to theUniversity of Pune during the year of this Re-port. The abstracts of the same are given be-low :

(i) Gravity at High Energies

Parampreet SinghUnderstanding of the initial conditions of

our universe is one of the frontier problems incurrent research. Standard model of cosmologyfails to address the issues concerned with veryearly history of the universe, near and abovePlanckian energies, which is related with thebreakdown of classical general relativity nearbig bang singularity. In this regime of gravity athigh energies, there is an interface of gravity andquantum, and the correct description can onlybe provided by a theory of quantum gravity. Itis expected that such a theory may also provideanswers to some unsolved problems in standardmodel of cosmology, like that of dark energy,matter-antimatter asymmetry, etc. This the-sis deals with investigations on the interface ofgravity and quantum, and cosmological implica-tions of candidate theories of quantum gravity.It is formatted in the following chapters.

Chapter 1 deals with an introduction to theproblem of quantization of gravity and its mo-tivations. The demand that a union of gen-eral relativity and quantum mechanics be selfconsistent and puts severe constraints restrict-ing the possible approaches to the problem. Ofthese, the most prominent are the string theo-retic approach based on ideas of particle physicsand canonical quantization or the loop quan-tum gravity based on Einsteinian philosophy ofspacetime. This chapter includes a discussionand comparison on these candidate theories.Apart from these mainstream approaches, wealso discuss some aspects of interface of quan-tum and gravity like gravity induced quantumphase shifts. Though the latter does not aim toaddress the issues of quantum gravity, it neverthe less offers some useful insights on the subtledomain where quantum and gravity meet whichis discussed in detail in Chapter 2.

Chapter 2 is based on the investigations re-lated to the effect of gravitational field on thequantum phase shifts. It is well known that anextended body possessing multipole moments

deviates from geodesic motion due to couplingof its multipole moments with the backgroundgravitational field. The effect of gravitationalfield on monopole moment of neutrons has beenempirically observed in interferometric experi-ments. However, in order to know the phaseshift due to dipole and higher multipole cou-plings with background gravitational field, wemust have an action principle formulation fordynamics of extended bodies in general relativ-ity. This is so because, the action is directlyobservable as the phase shift of the wavefunc-tion in the quantum theory. Dynamics of ex-tended bodies possessing multipole moments inexternal gravitational field, like motion of plan-ets, etc., is an important problem which cap-tures the effect of non negligible extension ofthe body in comparison to the radius of curva-ture of the background field. The coupling ofmultipole moments to the curvature generatescorrections to the geodesic equation, which wereobtained earlier for the case of spinning particlesand higher multipole moments. All these stud-ies focused on obtaining corrections by using theconservation of stress energy tensor. However,the problem to obtain these corrections from anaction principle remained unsolved for last 65years. In this chapter, we would discuss an el-egant action based procedure, which we haveestablished for the first time. It can, in a verysimple way compute the corrections to geodesicequation due to coupling of multipole momentsof any order with the gravitational field and theresultant phase shifts. The new phase shiftsmay be measurable in future interferometry ex-periments.

Chapter 3 deals with string inspiredbraneworld scenarios with an emphasis on as-pects of localization of gravity. In recent yearsthere has been a lot of studies related to largeextra dimensions and brane world scenariosmotivated by string theories. In particular,Randall-Sundrum models with warped extra di-mension have caught lot of attention. An im-portant feature of these models is to show thatextra dimension can be non compact and stillgravity can be localized on the brane. This isaccomplished through the effect of bulk curva-ture in the warp factor of the metric. One of theimportant problems in these scenarios is that oflocalization of gravity on the brane. This wasestablished originally by Randall and Sundrumfor the case of an anti de Sitter bulk with van-ishing Weyl and a flat brane with a vanishingcosmological constant. An immediate questionwhich arises in a more general setting is whethergravity is localized on the brane when Weyl cur-vature in the bulk is non vanishing. We study

this problem for bulk spacetimes with non zeroWeyl curvature in the bulk, in particular, forthe five dimensional generalization of the Nar-iai spacetime and the Schwarzschild-AdS space-time. In the former case, we show that a boundnormalizable massless mode can not exist onthe brane and thus, gravity can not be local-ized. The Schwarzschild-AdS bulk allows FRWcosmological branes and hence to understandlocalization of gravity in this case becomes animportant issue, if bulk-brane scenarios have tobe of any cosmological interest. The problembecomes difficult because of motion of brane,which makes difficult to impose boundary con-ditions. However, in a cosmological setting theimportant issue is whether conventional gravityis recovered on brane at late times of expansionof the universe when the brane is moving veryslowly. This would mean that over time scalesof interest brane can be treated as static. Forsuch a case, we show that a massless gravitonmode can be localized on the brane, providedthe effective cosmological constant on the braneis non negative. Thus, for brane cosmology, anon-negative cosmological constant is a definiteprediction.

In chapter 4, we study how large extra di-mension immediately opens up a new avenuefor studying cosmological consequences of suchmodels and even confront the ideas with cur-rent astronomical observations like supernovaand CMB. It is well known that warped braneworld cosmologies do not predict new and dis-tinct signatures from the standard cosmologiesat low energies. Earlier studies in the field es-tablished that the brane corrections to Fried-mann equation either die out at low redshifts orare severely constrained by the Big Bang nucle-osynthesis. Thus, it becomes difficult to haveany new low energy signature from the braneworld cosmology. However, corrections to bulk-brane action motivated by stress tensor regu-larization generate modifications to the effec-tive Friedmann equation, which gives distinctpredictions for brane cosmologies from those ofthe standard cosmological model at low ener-gies. Some of these corrections appear as sur-face term in the bulk-brane action and mod-ify the curvature term, which amounts to a dif-ference between the geometrical and dynamicalcurvature in FRW models. Such a model is dis-tinct from the standard model of cosmology atlow redshifts and thus, we can use astronomicalobservations to constrain it. We study fitting ofthis model with supernova Ia, position of peaksin CMB and quasar observations.

This chapter also deals with a related inves-tigation of cosmological dynamics of a phantom

field, which is inspired by string theory. As-trophysical observations like supernova Ia, haveconfirmed that our universe may be accelerat-ing. This has become one of the corner stoneissues of cosmology in recent years and manymodels have been proposed to explain this phe-nomena. Though the attempts are far from giv-ing any physically reasonable explanation, thereis an evolving consensus that this accelerationmay be caused by some sort of dark energy com-posed of exotic matter which may have an equa-tion of state less than -1. The only field theo-retic possibility for such an equation of stateis allowed through phantom scalar field whichhas negative kinetic energy. We study phantomscalar field in cosmological setting and use su-pernova Ia observations to constrain the modelparameters.

Chapter 5 deals with some cosmological im-plications of another candidate theory of quan-tum gravity, the loop quantum gravity. It isa non-perturbative canonical quantization ofgravity and one of the important questions itfaces is related with its semi-classical limit. Westudy two approaches, one based on coherentstates and the other on weave states. We discussconstruction of coherent states for constrainedsystems and extensions of weave states for theFermionic sector. For neutrinos, we discuss theway weave states introduce a new energy de-pendent scale and modifies the dispersion rela-tion for different helicities. For massless neu-trinos, this effect translates into a net neutrinoasymmetry and we argue that this can be oneof the physically viable mechanisms for gener-ating matter-antimatter asymmetry in the uni-verse after inflation. We also discuss construc-tion of semi-classical wormhole solutions usingcoherent state technique.

We conclude with summary of results andfuture directions in Chapter 6.

Publications:

The work reported in this thesis is based onthe following publications:

1. Parampreet Singh, and Naresh Dadhich,Non-conformally flat bulk spacetime andthe 3-brane world, Phys. Lett. B 511, 291(2001); hep-th/0104174.

2. G. Date, and Parampreet Singh, Semi-classical States in the context of con-strained cystems, quant-ph/0109127.

3. Parampreet Singh, and Naresh Dadhich,Localization of gravity in brane world cos-

mologies, Mod. Phys. Lett. A 18, 983(2003); hep-th/0204190.

4. Parampreet Singh, R. G. Vishwakarma,and Naresh Dadhich, Brane curvatureand supernovae Ia observations, hep-th/0206193.

5. Parampreet Singh, and Naresh Dadhich,Localized gravity on FRW branes, hep-th/0208080.

6. R. G. Vishwakarma, and ParampreetSingh, Can brane cosmology with a van-ishing Λ explain the observations ?, Class.Quant. Grav. 20, 2033 (2003); astro-ph/0211285.

7. Jeeva Anandan, Naresh Dadhich, andParampreet Singh, Action principle formu-lation for motion of extended bodies in gen-eral relativity, Phys. Rev. D 68, 124014(2003); gr-qc/0212130.

8. Gaetano Lambiase, and Parampreet Singh,Matter-antimatter asymmetry generatedby Loop quantum gravity, Phys. Lett. B565, 27 (2003); gr-qc/0304051.

9. Jeeva Anandan, Naresh Dadhich, andParampreet Singh, Action based approachto the dynamics of extended bodies in gen-eral relativity, Honorable Mention in Grav-ity Research Foundation Essay Competi-tion 2003, Int. J. Mod. Phys. D 12, 1651(2003); gr-qc/0305063.

10. Parampreet Singh, M. Sami, and NareshDadhich, Cosmological dynamics of phan-tom field, Phys. Rev. D 68, 023522 (2003);hep-th/0305110.

(ii) Physics of Structure For-mation in the Universe

Tirthankar Roy ChoudhuryIn recent years, our understanding of

the universe has been driven by tremendousprogress in observational cosmology, which hasrevealed a great deal of information about thegeometry, mass distribution and composition,and formation and evolution of structures ofthe universe. The observations of cosmic mi-crowave background radiation, consisting ofphotons reaching us from the era when theydecoupled from matter, have provided valuableinformation about the nature of our universeas it was about 10 billion years ago. The ob-servations of distribution of matter over very

large scales (say, ∼ 10 Mpc), studied throughgalaxy surveys, spectra of distant quasars andother measurements have provided informationabout the formation and evolution of structuresthat we see today. The redshift-magnitude mea-surements of the high redshift supernovae haveprovided information about the geometry, andhence, the energy density of the universe. Cur-rent and near future observations of gravitation-ally lensed objects will help us constrain thecosmological parameters to a very high accu-racy. The high accuracies in the measurementof most of the cosmological parameters helpedthe theoretical cosmologists to develop the socalled “standard model” of cosmology – a modelwhich is consistent with all the observations.

However, these observations have alsoleft the theoretical cosmologists with somechallenging issues. For example, we do nothave any laboratory evidence for about 95 percent of the matter component in the universe.About one third of these is a non-relativisticpressure-less fluid which does not interact withradiation, while the rest two-third is a negativepressure component. Similarly, we still do nothave satisfactory models which describe thephysics of the formation of baryonic structures,like galaxies, in the universe. In this thesis,we have addressed two key issues in this field,namely, (i) the formation of baryonic structures(Chapters 2–5), and (ii) the nature of darkmatter and dark energy, and the limitationsin determining their nature from observations(Chapter 6). Although tremendous progresshas been achieved in studying the baryonicphysics in the universe through numerical sim-ulations, the computational cost has preventedus from achieving high enough numericalresolution so as to understand the physical pro-cesses in detail. In this regards, we have takenthe approach of analytical and semi-analyticalmodelling, which do not have the problemof computational power. The analytical andsemi-analytical models described in this thesisare found to match excellently with current ob-servational data, and can be further comparedwith improved datasets expected in near future.

A chapter wise summary of the thesis isgiven below:

The first chapter reviews some of the basicconcepts in cosmology and structure formationneeded for the rest of the thesis. We have dis-cussed very briefly the basic features of the stan-dard model of cosmology. The standard modelis studied in the framework of Einstein’s generaltheory of relativity. The line element appropri-ate for an expanding universe, which is homo-

geneous and isotropic at large scales is given bythe Friedmann metric. It describes the geome-try of the smooth background universe, which isreviewed very briefly in this chapter. The obser-vations indicate that the composition of the uni-verse consists of normal matter (baryons), ra-diation, and two unknown components of darkmatter and dark energy.

The formation of structures are believed tobe because of the growth of small ‘seed’ per-turbations (mainly dark matter and baryonic)via gravitational instability. We have describedthe evolution and statistics of these perturba-tions (both in dark matter and baryons) in theframework of linear as well as non-linear the-ory. The interaction of the baryons with theradiation cause tremendous difficulties in devel-oping a non-linear theory for baryonic perturba-tions. A major part of the thesis is devoted tomodelling these non-linearities. Finally, we havedescribed the thermal history of the baryonsand formation of baryonic structures in the uni-verse. The neutral baryons fall into the poten-tial wells created by the massive dark matterhaloes. These baryons can form galaxies pro-vided they are able to cool and fragment withinthe dark matter haloes. As the first stars form,the ultraviolet radiation emitted by them ion-ize the nearby low density baryons in the inter-galactic medium – the process is called ‘reion-ization’. We have discussed the current under-standing of the basic physical processes leadingto the reionization and the physical conditionsin the diffuse intergalactic medium.

In Chapter 2, we introduce an approxima-tion scheme for the non-linear baryonic massdensity – the lognormal ansatz. Analyticalderivations of the correlation function and thecolumn density distribution for neutral hydro-gen in the intergalactic medium (IGM) are pre-sented, assuming that the baryonic mass den-sity distribution in the IGM follows the lognor-mal ansatz. This ansatz was used earlier by Biand Davidsen to perform one-dimensional sim-ulations of lines of sight and analyse the prop-erties of absorption systems. We have taken acompletely analytical approach, which allows usto explore a wide region of the parameter spacefor our model. The analytical results have beencompared with observations to constrain vari-ous cosmological and IGM parameters, when-ever possible. Two kinds of correlation func-tions are defined : (i) along the line of sight(LOS); and (ii) across the transverse direction.We find that the effects on the LOS correlationowing to changes in cosmology and the slopeof the equation of state of the IGM, γ are ofthe same order, which means that we cannot

constrain both the parameters simultaneously.However, it is possible to constrain γ and itsevolution using the observed LOS correlationfunction at different epochs provided that oneknows the background cosmology. We suggestthat the constraints on the evolution of γ ob-tained using the LOS correlation can be usedas an independent tool to probe the reioniza-tion history of the universe. From the trans-verse correlation function, we obtain the excessprobability, over random, of finding two neutralhydrogen overdense regions separated by an an-gle θ. We find that this excess probability isalways less than 1 per cent for redshifts greaterthan 2. Our models also reproduce the observedcolumn density distribution for neutral hydro-gen, and the shape of the distribution dependson γ. Our calculations suggest that one canrule out γ > 1.6 for z ' 2.31 using the columndensity distribution. However, one cannot rulehigher values of γ at higher redshifts.

In Chapter 3, we extend the analyticalcalculations of the previous chapter and per-form one-dimensional semi-analytical simula-tions along the lines of sight to model the IGM.Since this procedure is computationally efficientin probing the parameter space – and reason-ably accurate – we use it to recover the val-ues of various parameters related to the IGM(for a fixed background cosmology) by compar-ing the model predictions with different obser-vations. For the Λ cold dark matter model(Ωm = 0.4, ΩΛ = 0.6 and h = 0.65), we ob-tain, using statistics obtained from the trans-mitted flux, constraints on (i) the combinationf = (ΩBh2)2/J−12, where ΩB is the baryonicdensity parameter and J−12 is the total pho-toionization rate in units of 10−12s−1, (ii) tem-perature T0 corresponding to the mean den-sity, and (iii) the slope γ of the effective equa-tion of state of the IGM at a mean redshiftz ' 2.5. We find that 0.8 < T0/(104K) < 2.5and 1.3 < γ < 2.3, while the constraint ob-tained on f is 0.0202 < f < 0.0322. A reli-able lower bound on J−12 can be used to put alower bound on ΩBh2, which can be comparedwith similar constraints obtained from big bangnucleosynthesis (BBN) and cosmic microwavebackground radiation (CMBR) studies. We findthat if J−12 > 1.2, the lower bound on ΩBh2 isin violation of the BBN value.

Chapter 4 deals with comparatively highdensity regions, namely, the damped Lyα sys-tems (DLAs). The DLAs are identified withthe lines having highest column densities in atypical observed absorption spectrum of a dis-tant quasar. These high column density systemsare important in understanding the baryonic

structure formation, because they contain a fairamount of the neutral hydrogen in the universeat high redshifts. As a preliminary study for un-derstanding these systems, a simple analyticalmodel for estimating the fraction (Ωgas) of mat-ter in gaseous form within the collapsed darkmatter (DM) haloes is presented. The modelis developed using (i) the Press-Schechter for-malism to estimate the fraction of baryons inDM haloes, and (ii) the observational estimatesof the star formation rate at different redshifts.The prediction for Ωgas from the model is inbroad agreement with the observed abundanceof the damped Lyα systems. Furthermore, itcan be used for estimating the circular veloci-ties of the collapsed haloes at different redshifts,which could be compared with future observa-tions.

In Chapter 5, we take our first step to-wards modelling the reionization. We explorethe possibility of using the properties of gamma-ray bursts (GRBs) to probe the physical condi-tions in the epochs prior to reionization. TheGRBs are among the brightest sources in thesky in any wavelength region. They are be-lieved to originate due to collapse of very mas-sive stars in the galaxies. In this chapter, theredshift distribution of GRBs is modelled usingthe Press-Schechter formalism with an assump-tion that they follow the cosmic star formationhistory. We reproduce the observed star forma-tion rate obtained from galaxies in the redshiftrange 0 < z < 5, as well as the redshift distribu-tion of the GRBs inferred from the luminosity-variability correlation of the burst light curve.We show that the fraction of GRBs at high red-shifts, the afterglows of which cannot be ob-served in R and I band owing to Hi Gunn-Peterson optical depth can, at the most, accountfor one third of the dark GRBs. The observedredshift distribution of GRBs, with much lessscatter than the one available today, can putstringent constraints on the epoch of reioniza-tion and the nature of gas cooling in the epochsprior to reionization.

Chapter 6 deals with issues related to thenature of dark matter and dark energy. Cur-rent cosmological observations strongly suggestthe existence of two different kinds of energydensities dominating at small (. 500 Mpc) andlarge (& 1000 Mpc) scales. The dark mattercomponent, which dominates at small scales,contributes Ωm ≈ 0.35 and has an equationof state p = 0, while the dark energy com-ponent, which dominates at large scales, con-tributes ΩΛ ≈ 0.65 and has an equation of statep ' −ρ. The most obvious candidate for thisdark energy is the cosmological constant (with

the equation of state wX = p/ρ = −1), which,however, raises several theoretical difficulties.This has led to models for dark energy compo-nent which evolves with time. We discuss cer-tain questions related to the determination ofthe nature of dark energy component from ob-servations of high redshift supernova. The mainresults of our analysis are: (i) Even if the precisevalue of wX is known from observations, it is notpossible to determine the nature of the unknowndark energy source using only kinematical andgeometrical measurements. We have given ex-plicit examples to show that different types ofsources can give rise to a given wX . (ii) It isusual to postulate weakly interacting massiveparticles (WIMPs) for the dark matter compo-nent and some form of scalar field or cosmo-logical constant for the dark energy component.We explore the possibility of a scalar field witha Lagrangian L = −V (φ)

√1− ∂iφ∂iφ acting as

both clustered dark matter and smoother darkenergy, and having a scale-dependent equationof state. This model predicts a relation betweenthe ratio r = ρV /ρDM of the energy densities ofthe two dark components and expansion raten of the universe [with a(t) ∝ tn] in the formn = (2/3)(1+r). For r ≈ 2, we get n ≈ 2 whichis consistent with current supernova observa-tions. (iii) It is well known that the full dataset of supernova observations (which are cur-rently available) strongly rule out models with-out dark energy. However, the high (z > 0.25)and low (z < 0.25) redshift data sets, individu-ally, admit decelerating models with zero darkenergy. This implies that any possible evolutionin the absolute magnitude of the supernovae, ifdetected, might allow the decelerating modelsto be consistent with the data. This certainlyappears ad-hoc; but one should compare thead-hocness in these assumptions with the ad-hocness in introducing a dimensionless constantΛ(G~/c3) ≈ 10−123 in the physical system toexplain the cosmological observations. (iv) Theevolution of the dark energy component can beparametrized by its equation of state parame-ter wX(z). We have examined the possibilityof constraining wX(z) by comparing theoreticalmodels with supernova observations. In this re-gard, we have introduced two parameters, whichcan be obtained entirely from theory, to studythe sensitivity of the luminosity distance on wX .Using these two parameters, we have arguedthat although one can determine the presentvalue of wX accurately from the data, it is muchmore difficult to determine the evolution of wX

unambiguously.Finally, the main conclusions of the thesis

are summarized in Chapter 7. We have also

commented on how some of the work describedin the thesis can be extended further in nearfuture.

Publications:

The thesis is mainly based on the followingpublications:

• T. Padmanabhan and T. Roy Choudhury(2003) A theoretician’s analysis of the super-nova data and the limitations in determiningthe nature of dark energy, MNRAS 344, 823astro-ph/0212573

• T. Padmanabhan and T. Roy Choud-hury (2002) Can the clustered dark matterand the smooth dark energy arise from thesame scalar field?, Phys. Rev. D 66, 081301hep-th/0205055

• T. Roy Choudhury and R. Srianand(2002) Probing the dark ages with redshiftdistribution of gamma ray bursts, MNRAS 336,L27 astro-ph/0205446

• T. Roy Choudhury and T. Padmanabhan(2002) A simple analytical model for the abun-dance of damped Lyα absorbers, ApJ 574, 59astro-ph/0110359

• T. Roy Choudhury, R. Srianand and T.Padmanabhan (2001) Semianalytic approach tounderstanding the distribution of neutral hydrogenin the Universe: comparison of simulations withobservations, ApJ 559, 29 astro-ph/0012498

• T. Roy Choudhury, T. Padmanabhanand R. Srianand (2001) Semianalytic approachto understanding the distribution of neutralhydrogen in the universe, MNRAS 322, 561astro-ph/0005252

76

(IV) PUBLICATIONS

By IUCAA Academic Staff

The publications are arranged alphabetically by the nameof the IUCAA staff member, which is highlighted in thelist of authors. When a paper is co-authored by an IUCAAstaff member and a Visiting Associate of IUCAA, thename of the latter is displayed in italics.

(a) Journals

Alam, Ujjaini, Varun Sahni, and A. A. Starobinsky (2004)The case for dynamical dark energy revisited, JCAP, 0406,008.

Alam, Ujjaini, Varun Sahni, Tarun Saini and AlexeiStarobinsky (2004) Is there supernova evidence for darkenergy metamorphosis ? MNRAS, 354, 275.

Ahuja, A. L., Y. Gupta, D. Mitra and A. K. Kembhavi(2005) Tracking pulsar dispersion measures using theGiant Metrewave Radio Telescope, MNRAS, 357, 1003.

Chand, H., Petitjean, P., Srianand, R., and Aracil, B., (2005)Probing the cosmological variation of the fine-structureconstant II: Results based alkali doublets in VLT-UVESsample, A&A, 430, 47.

Dadhich N., S.G. Ghosh and D.W. Deshkar (2005) TheRole of space-time dimensions and the fluid equation ofstate in spherical gravitational collapse, Int. J. Mod. Phys.A, 20, 7, 1495.

B. Mukhopadhyay and N. Dadhich (2004) Scalar andspinor perturbations to the Kerr-NUT spacetime, Class.Quant. Grav., 21, 362.

Joshi, P.S., R. Goswami and N. Dadhich (2004) Why donaked singularities form in gravitational collapse? - II,Phys. Rev. D, 70, 087502.

Kar, S., N. Dadhich and M. Visser (2004) Quantifyingenergy condition violation in traversable wormholes,Pramana, 63, 859.

Shankaranarayanan, S. and N. Dadhich (2004) Non-singular black holes on the brane, Int. J. Mod. Phys., D13,1095.

Dhurandhar S. V. (2004) Data analysis techniques forgravitational wave observations, Pramana, 20, 717.

Dhurandhar S.V., R. Nayak, S. Koshti and J-Y. Vinet (2005)Fundamentals of LISA stable flight formation, Class.Quant. Grav., 22, 481.

Dhurandhar S.V. and LIGO collaboration (~ 200 authors)(2004) First upper limits from LIGO on GW bursts, TheLigo Science Collaboration, Phys. Rev. D 69, 10200.

Dhurandhar S.V. and LIGO collaboration (~ 200 authors)(2004) Analysis of LIGO data for GW from Binary NeutronStars, The LIGO Science Collaboration, Phys. Rev. D, 69,122001.

Dhurandhar S.V. and LIGO collaboration (~ 200 authors)(2004) Analysis of LIGO data for Stochastic GW, The LIGOScience Collaboration, Phys. Rev. D,69, 122004.

Dhurandhar S.V. and LIGO collaboration (~ 200 authors)(2004) Setting upper limits on the strength of periodicGW from PSR 1939+2134 using the first science data fromthe GEO600 and the LIGO detectors, The LIGO ScienceCollaboration, Phys. Rev. D,69, 082004.

Ranade, A.C., N.M. Ashok, Ranjan Gupta and HarinderP. Singh (2004) A Near-Infrared Stellar Spectral Library: IH-Band Spectra BASI, 32, 311-333.

Valdes, Francisco, Ranjan Gupta, James A. Rose, HarinderP. Singh and David J. Bell (2004) The Indo-U.S. library ofCoude Feed stellar spectra, Astrophys. J. Supp, 152n2,251.

Gupta Ranjan, Harinder P. Singh, Kevin Volk and S. Kwok(2004) Automated classification of 2000 bright IRASsources, Astrophys. J. Supp., 152 n2, 201.

Hajian, Amir, Tarun Souradeep and Neil Cornish (2005)Statistical isotropy in the WMAP data: Bipolar powerspectrum of CMB, Astrophys. J. Lett., 618, L63-L66.

Jassal, H. K. J.S. Bagla and T. Padmanabhan (2005) WMAPconstraints on low redshift evolution of dark energy,MNRAS Letters, 356, L11-L16.

Barway, Sudhanshu, Mayya, Y. D., Ajit Kembhavi andPandey, S. K. (2005) Multicolour surface photometry oflenticular galaxies. I. The Data Astron. J., 129, 630.

Misra, R. and K. Shanthi (2004) On the incidence ofkilohertz quasi-periodic oscillations in the neutron starsystem 4U 1636-53, MNRAS, 354, 945.

Misra, R. K. P. Harikrishnan, B. Mukhopadhyay, G.Ambika and A. K. Kembhavi (2004) The Chaotic Behaviorof the Black Hole System GRS 1915+105, Ap.J., 609, 313.

Mitra, Sanjit, Anand S. Shankar and Tarun Souradeep(2004) Power spectrum estimation of CMB anisotropyusing non-circular beams, Phys Rev. D,70 103002.

Andrei P. Sommer, Norimune Miyake, N. ChandraWickramasinghe, Jayant V. Narlikar and Shirwan Al-

77

Mufti (2004) Functions and possible provenance ofprimordial proteins, Journal of Proteome Research, 3, 6,1296.

Padmanabhan, T. (2004) Gravitational entropy of staticspacetimes and microscopic density of states, Class.Quant. Grav., 21 , 4485.

Padmanabhan, T. (2004) Entropy of horizons, complexpaths and quantum tunneling, Mod. Phys. Letts. A, 19,2637.

Padmanabhan, T. (2004) Gravity as elasticity of spacetime:A paradigm to understand horizon thermodynamics andcosmological constant, Int. J. Mod. Phys. D, 13 2293.

Padmanabhan, T. (2005) Gravity and the thermodynamicsof horizons, Phys. Reports, 406, 49.

Padmanabhan, T. (2005) Dark energy: The cosmologicalchallenge of the millennium, Current Science, 88,1057.

Choudhury, T. Roy and T. Padmanabhan (2005)Cosmological parameters from supernova observations:A critical comparison of three data sets, A &A, 429, 807.

Sriramkumar, L. and T. Padmanabhan (2005) Initial stateof matter fields and trans-Planckian physics: Can CMBobservations disentangle the two? Phys. Rev.D, D 71103512.

S. Ray, J. S. Bagla and T. Padmanabhan (2005) Gravitationalcollapse in an expanding universe: Scaling relations fortwo-dimensional collapse revisited, MNRAS, 360, 546.

M. Sami and N. Dadhich (2004) Unifying brane worldinflation with quintessence, Vestnik TSPU, 7, 25.

M. Sami and Varun Sahni (2004) Quintessential inflationon the brane and the relic gravity wave background, Phys.Rev. D,70, 083513.

Shandarin, Sergei, Jatush Sheth and Varun Sahni (2004)Morphology of the supercluster-void network in LCDMcosmology, MNRAS, 353, 162.

Petitjean, P., A. Ivanchik, R. Srianand, Varshalovich, D.,Chand, H., Rodrigues, E., Ledoux, C., Boisse, P., (2004)Time dependence of the proton-to-electron mass ratio, C.R. Physique, 5, 411.

Stalin, C. S. and R. Srianand (2005) Long-term opticalphotometric monitoring of the quasar SDSS J153259.96-003944.1, MNRAS, 308.

Arman Shafieloo and Tarun Souradeep (2004) Primordialpower spectrum from WMAP, Phys. Rev. D, 70, 043523,1.

Jeremiah P. Ostriker and Tarun Souradeep (2004) Thecurrent status of observational cosmology, Pramana, 63,817.

Subramanian, K. and A. Brandenburg, (2004) Nonlinearcurrent helicity fluxes in turbulent dynamos and alphaquenching, Phys. Rev. Lett., 93, 205001, 1.

Sethi, S. K. and K. Subramanian (2005) Primordialmagnetic fields in the post-recombination era and earlyreionization, MNRAS., 356, 778.

Subramanian, K. (2005) The physics of CMBRanisotropies, Current Science, 88, 1068.

Becker, P. A. and P. Subramanian (2005) Restrictions onthe form for the viscosity in advection-dominatedaccretion disks, Ap.J., 622, 520.

Subramanian, P., Becker, P. A.(2004) Noise-stormcontinua: Power estimates for electron acceleration, SolarPhysics, 255, 91.

(b) Proceedings

Dadhich N. (2004) Summary of Classical GeneralRelativity Workshop, Proceedings of the FifthInternational Conference on Gravitation and Cosmology,Pramana 63, 4, 887.

S. V. Dhurandhar (2003) Gravitational Waves: CurrentStatus, in Man and the Universe in the symposiumFrontiers of Astrophyics and Cosmology in the 2ndInternational Conference for Science Communicators,Mumbai, held during June 20 - 22, Eds. Parul Sheth, S.Naikh-Satam, A.P. Deshpande, (NCSC) p. 42.

Quinn, Peter J., Barnes David G., Csabai Istvn, CuiChenzhou, Genova Franoise, Hanisch Bob, AjitKembhavi , Kim Sang Chul, Lawrence Andrew andMalkov Oleg, (2004) The International Virtual ObservatoryAlliance: Recent technical developments and the roadahead SPIE Proceedings, 5493, p.137.

Kembhavi, Ajit, Hegde Hrishikesh, Kale Sonali, KrishnanP. R., Navelkar Vasudev and Vijayaraman T. M. (2004) AC++ Parser for VOTables, Proceedings of the ESO/ESA/NASA/NSF Conference. Edited by P.J. Quinn, and K.M.Gorski. Springer, p. 124.

Kale S., Vijayaraman T. M., Kembhavi A., Krishnan P. R.,Navelkar,A.,Hegde, H., Kulkarni P., Balaji K. D. (2004)VOPlot: A toolkit for scientific discovery using VOTablesProc. ADASS XIII Conference. Edited by FrancoisOchsenbein, Mark G. Allen and Daniel Egret. ASPConference Proceedings,Vol. 314.

78

Kulkarni P., Kembhavi A., Kale S. (2004) VOTable JAVAstreaming writer and applications. ASPC Proceedings, Vol314, p. 346.

Srianand, R., et al. (2004) Constraining the time variationof fine-structure constant, Msngr (Quarterly journalpublished by European Southern Observatory), 116, 25.

Bergeron, J. Srianand, R., et al., (2004) The largeprogramme “cosmic evolution of the IGM”, Msngr ,(Quarterly journal published by European SouthernObservatory), 118, 40.

Shaw, G., Ferland, G.J., Srianand, R. (2004) Spectroscopicsignatures of star formation in DLAs, AAS, 20512902S

Shaw, G., Ferland, G. J., Stancil, Srianand, R. (2004) Validityof H

2 as a kinetic tracer, AAS, 2046120.

Narlikar, J.V. (2005) Alternative ideas in cosmology,The Scientific Legacy of Fred Hoyle, Ed. D. Gough,(Cambridge University Press), 127.

Padmanabhan, T. (2003) Weight of the Vacuum, in Manand the Universe in the symposium Frontiers ofAstrophyics and Cosmology in the 2nd InternationalConference for Science Communicators, Mumbai, heldduring June 20 - 22, Eds. Parul Sheth, S. Naikh-Satam, A.P.Deshpande, (NCSC) p. 37.

Varun Sahni (2005) Dark matter and dark energy; In ‘ThePhysics of the Early Universe’, Proceedings of the 2ndAegean Summer School on the Early Universe, Ermoupoli,Island of Syros, Greece; Editor E. Papantonopoulos,Springer 2005 p. 141.

Tarun Souradeep (2005) Statistical isotropy of CMBanisotropy from WMAP Proceedings of the Fourteenthworkshop on General Relativity and Gravitation in JapanEds. W. Hikida, M. Sasaki, T. Tanaka and T. Nakamura p.62.

Tarun Souradeep (2004) Summary of ICGC-04 CosmologyWorkshop Chairperson’s Summary : Proceedings of theInternational Conference on Gravitation and Cosmology,Pramana 63, 891.

(c) Books (authored/edited)

Narlikar, J.V. (2004)[authored] [in Marathi] KhagolShastra : Prasnotare, Marathi Vidnyan Parishad, Mumbai.

Narlikar, J.V. (2005) [authored] Black Holes, NationalBook Trust, India, New Delhi.

Narlikar, J.V. (2005) [authored] Tales of the Future,Witness Books, Delhi.

T. Padmanabhan

The following popular science book published by VigyanPrasar, New Delhi has now been translated into Telugu.The Story of Physics [a comic strip with figurescontributed by Keith Francis and Avinash Deshpande,based on the author’s ideas], Vigyan Prasar, New Delhi,2002.

(d) Book Review

Dadhich N. (2004) Explaining the Universe by John M.Charap, Current Science, 87, 11, 1619.

(e) Technical Report

J.V. Narlikar (2004)- Chaire internationale, Cours et travaluxdu College De France, 1141.

79

Publications by Visiting Associatesand Long Term Visitors

The publications are arranged alphabetically by the nameof visiting Associates, which is highlighted in the list ofauthors.

(a) Journals

Chatterjee, S. and Asit Banerjee (2004) C – fieldcosmological model in higher dimensions, Gen. Rel. Grav.,36, 303.

Banerjee, A., U. Debnath and S. Chakraborty (2004)Higher Dimensional Szekers’ space-time in Brans-DickeScalar-Tensor theory, Int. J. Mod. Phys. D, 13, 1073.

Debnath, U., A. Banerjee and S. Chakraborty (2004) Roleof modified Chaplygin gas in accelerated universe, ClassQuant. Grav. 21, 5609.

Chakraborty, D. K. (2004) Ellipsoidal mass models with

varying, A & A, 423, 501.

Chakraborty, S. and U. Debnath (2004) A Study of higherdimensional inhomogeneous cosmological model, Int. J.Mod. Phys. D, 13, 1085.

Debnath, U. and S. Chakraborty (2004) GravitationalCollapse in higher dimensional space-time, Gen. Rel. Grav.36, 1243.

Debnath, U. and S. Chakraborty (2004) Naked singularityin higher dimensional Szekers’ space–time, J. Cosmologyand Astroparticle Physics 5, 001.

Nath, S., S. Chakraborty and U. Debnath (2004)Anisotropic Brane Cosmology with variable G and Ë,J. Cosmology and Astroparticle Physics,11, 012.

De, A. K., S. Bhanja and S. Chakraborty (2004) StringCosmology in Brane world Scenarios, Gen.Rel. Grav. 36,863.

Chakraborty, N. C. and S. Chakraborty (2004) GeneralizedScalar-Tensor theory for Bianchi space-time models, Mod.Phys. Lett. A, 19, 703.

Chandra, D. and A. Goyal (2004) Effects of Curvature andInteractions on the Dynamics of the Deconfinement PhaseTransition, Int. J. Mod. Phys. A, 19, 5221.

Chandra, Suresh (2004) Comments on universal relationbetween spectroscopic constants, Pramana, 62, C1181.

Chandra, Suresh and S. A. Shinde (2004) Suggestionsfor an interstellar C

5H

2 search, A & A, 423, 325.

Chandra, Suresh (2004) Search for an interstellar Si2C

molecule: A theoretical prediction, Pramana, 63, 627.

Chandra, Suresh (2004) On temperature T01

for molecularhydrogen, Ind. J. Phys. B, 78, 1395.

Bagchi, Manjari, Mira Dey, Sukanta Daw and Jishnu Dey(2004) A Model Finding a new Richardson Potentialwith different scales for confinementand asymptotic freedom, by propertiesof Ä++ and ?-, Nuclear Physics, A 740, 109.

Bhaduri, R. K., J. Sakhr, D.W.L. Sprung, R. Dutt and A.Suzuki (2005) Shape invariant potentials in SUSY quantummechanics and periodic orbit theory, J. Phys. A: Math.Gen. 38, L183.

Parvate, Abhay and A. D. Gangal (2005) Fractal differentialequations and fractal-time dynamical systems, Pramana,64, 389.

Dawood, A. K., S. G. Ghosh (2004) Generating dynamicalblack hole solutions, Phys. Rev. D 70, 104010.

Ghosh, S. G. (2005) Inhomogeneous dust collapse withcosmological constant, Int. J. Mod. Phys. D., 14, 707.

Goyal, A. K., S. Rai Choudhury, Naveen Gaur and NamitMahajan (2004) B-B_bar mass difference in Little HiggsModel, Phys. Lett. B, 601, 164.

Harikrishnan, K. P. and G. Ambika (2005) Stochasticresonance in a model for Josephson Junction – PhysicaScripta, 71, 148.

Ibohal, Ng. (2005) Rotating metrics admitting non-perfectfluids, Gen. Rel. Grav., 37, 19.

Indulekha, K., G. V. Vijayagovindan, S. Ramadurai (2004)Collapse of an inhomogeneous protogalaxy with randommotions, Adv. Space Res. 34, 670.

Dev, Abha, Deepak Jain and S. Mahajan (2004) DarkEnergy and the Statistical Study of the Observed ImageSeparations of the Multiply Imaged Systems in the CLASSStatistical Sample, Int. J. Mod. Phys. D, 13, 1005.

Dev, Abha, Deepak Jain and Jailson S. Alcaniz (2004)Constraints on Chaplygin quartessence from the CLASSgravitational lens statistics and supernova data, A & A,417, 847.

Bournaud, F., F. Combes, and C. J. Jog (2004) Unequal-mass galaxy merger remnants: Spiral-like morphology butelliptical-like kinematics, A & A, 418, L27.

80

John, Moncy V. (2004) Cosmographic Evaluation ofDeceleration Parameter Using Type Ia Data, ApJ. 614, 1.

Kaushal, R. S., D. Parashar and A. K. Sisodiya (2004) Amodel for pentaquark baryons and tetraquark mesons,Phys. Lett. B 600, 215.

Kaushal, R. S. (2004) What remains invariant?, GanitBharati (Delhi), 26, 1.

Kaushal, R. S. (2005) Diffusion-reaction (D-R) Hamiltonianand the solution of certain types of linear and nonlinearD-R equations in one dimension, J. Phys. A: Math & Gen,38, 1.

Gupta, M. R., S. Sarkar, B. Roy, A. Karmakar, ManoranjanKhan (2004) Effect of secondary electron emission on thepropagation of dust acoustic waves in dusty plasma, Phys.Plasmas, 11, 1850.

Ghosh, S., R. Bharuthram, Manoranjan Khan and M. R.Gupta (2004) Instability of dust acoustic wave due to non-thermal ions in a charge varying dusty plasma, Phys.Plasmas 11, 3602.

Bhattacharyya, K., T. Guha, R. Bhar, V. Ganesan,Manoranjan Khan and R. L. Brahmachary (2004) Atomicforce microscopic studies on erythrocytes from anevolutionary perspective, J. Anatomical Record Part A297, 671.

Khare, Pushpa, V. P.Kulkarni, J. Lauroesch, D.G. York,A.P.S. Crotts, and O. Nakamura (2004) Metals and dust inintermediate redshift Damped Lyman alpha galaxies, ApJ,616, 86.

Kulkarni, V. P., S. M. Fall, J. Lauroesch, D. G. York, D.Welty, Pushpa Khare and J.W. Truran (2005) HubbleSpace Telescope observations of element abundances inlow redshift damped Lyman alpha galaxies and implicationsfor the global metallicity-redshift relation, ApJ, 618, 68.

Kumar, V., Srivastava, K. M., Kumar, N. and Sikka, H.(2004) Kelvin- Helmholtz instability in a rotating ideallyconducting inhomogeneous plasma, Pramana, 62, 899.

Sikka, H., Kumar, N and Zhelyazkov, I. (2004) Surfacewave propagation in an ideal Hall-magnetohydrodynamicplasma jet in flowing environment, Phys. Plasmas, 11, 4904.

Shaju, P. D. and V. C. Kuriakose (2004) Static and rfmagnetic field effects on fluxon dynamics in semiannularJosephson junctions, Phys. Rev. B., 70, 064512.

Shaju, P. D. and V. C. Kuriakose (2004) Double-wellpotential in annular Josephson junction; Phys. Lett. A,332, 326.

Kuriakose, P. I. and V. C. Kuriakose (2004) Back reactionin static Einstein spaces - change of entropy, Gen. Rel.Grav. 36, 2433.

Mondal, K. K. (2004) Propagation of dust-acoustic wavesin weakly ionized plasmas with dust charge fluctuation,Pramana, 63, 1021.

Mondal, K. K., Bhattacharya, S. K. and Paul S. N. (2004)Linear and nonlinear propagation of ion-acoustic wavesin a bounded plasma containing negative ions, Fizika A,13, 77.

Nandi, K. K., Yuan-Zhong Zhang and K.B. Vijaya Kumar(2004) Volume Integral Theorem for Exotic Matter, Phys.Rev. D, 70, 127503.

Nandi, K. K., Yuan-Zhong Zhang and K.B. Vijaya Kumar(2004) Semiclassical and Quantum Field Theoretic Boundsfor Traversable Lorentzian Stringy Wormholes, Phys. Rev.D, 70, 064018.

Nandi, K. K., Yuan-Zhong Zhang (2004) On TraversableLorentzian Wormholes in the Vacuum Low EnergyEffective String Theory in Einstein and Jordan Frames,Phys. Rev. D, 70, 044040.

Barway, S., and S. K. Pandey (2004) HD52452: New BVRPhotometry, IBVS, 5553, 1.

Barway, S., S. K. Pandey and P. S. Parihar (2005) BVRPhotometry of a newly identified RSCVn binary starHD61396, 2004, New Astronomy, 10, 109.

Bhardwaj, Somnath and Sanjay K. Pandey (2005) Probingnon-Gaussian features in the HI distribution at the epochof reionization, MNRAS, 358, 968.

Pandey, Sanjay K. and Daksh Lohiya et. al. (2005) A casefor nucleosynthesis in the slowly evolying models,Spacetime and Substance, 6, 31.

Pandey, U. S. (2004) On gravitating stellar systems I.formation using distribution function method, BASI, 32,141.

Paul, B. C. (2004) Relativistic Star solution in HigherDimensions, Int. J. Mod. Phys. D, 13, 229.

Paul, B. C. and M. Sami (2004) A note on TachyonicInflation on the Gauss Bonnet Brane, Phys. Rev. D, 70,027301.

Abraham, Ajith, Sajith Philip and P.K. Mahanti (2004)Soft computing models for weather forecasting,International Journal of Applied Science andComputations, USA, Vol. 11 No.3, 106.

81

Pradhan, A. and S. K. Singh (2004) Bianchi type Imagnetofluid cosmological models with variablecosmological constant revisited, Int. J. Mod. Phys. D, 12,503.Pradhan, A. and H. R. Pandey (2004) Bulk viscouscosmological models in Barber’s second self creationtheory, Ind. J. Pure Appl. Math. 35, 513.

Pradhan, A. and Abha Rai (2004) Tilted Bianchi type Vbulk viscous cosmological models in general relativity,Astrophys. Space Sci., 291, 149.

Pradhan, A. and O.P. Pandey (2004) Tilted Bianchi type Iuniverse for barotropic perfect fluid in general relativityand spacetime and substance, 5 No. 4 (24), 149.

Pradhan, A. and S. K. Singh (2004) Generation of Bianchitype V cosmoloical models with varying Λ −term,spacetime and substance, 5, No.3 (23), 97.

Lohani, N. K. and Lalan Prasad (2004) Heating of solarcoronal loops by phase-mixing, Spacetimes andSubstance, 5, 57.

Radhakrishnan, R. and R. Babu Thayyullathil (2004)Nonresonant multiphoton ionization in atomic hydrogen,Phys. Rev. A, 69, 033407.

Pathak, Amit and Shantanu Rastogi (2005) Computationalstudy of neutral and cationic catacondensed PolycyclicAromatic Hydrocarbons, Chemical Physics, 313, 133.

Ray, Saibal, and S. Bhadra (2004) Classical electronmodel with negative energy density in Einstein-Cartantheory of gravitation, Int. J. Mod. Phys. D, 13, 555.

Reddy, R. R., Y. Nazeer Ahammed, K. Rama Gopal and D.Baba Basha (2004) Spectroscopic investigations on cometmolecules CO+, CH and CH+, J. Quant. SpectroscopicRadiat. Transfer 85, 105.

Erjaee, G. H., M. H. Atabakzade and L. M. Saha (2004)Interesting synchronization –like behaviour, Int. J.Bifur.and Chaos, 14, 1147.

Ali, M., L. M. Saha, Yasuo Tanaka and Hideo Soga (2005)Non parametric periodic orbit as a singularity og OGYstabilization technique, Bull.Fac.Edu.Ibaraki, Univ.(Nat.Sci), 54, 121.

Ali, M., L. M. Saha, Yasuo Tanaka and Hideo Soga (2005)Bifurcation Scenario in Gumowski-Mira map: Chaosdoubling phenomenon, Bull.Fac.Edu.Ibaraki, Univ.(Nat.Sci), 54, 129.

Ali, M., and L. M. Saha (2005) Local Lyapunov exponentsand characteristics of fixed/ periodic points embedded

within a chaotic attractor, J. Zhejiang Univ.Sci, 6A, 296.

Krot, A. N., T. J. Fagan, K. Keil, K. D. McKeegan, S.Sahijpal, I. D. Hutcheon, M. I. Petaev and H. Yurimoto(2004) Ca-Al-rich inclusions, amoeboid olivine aggregates,and Al-rich chondrules from the unique carbonaceouschondrite Acfer 094: I. mineralogy and petrology,Geochim. Cosmochim. Acta, 68, 2167.

Dufaux, Jean-Francois, James E. Lidsey, Roy Maartens,M. Sami (2004) Cosmological perturbations from braneinflation with a Gauss-Bonnet term, Phys. Rev. D70083525.

Edmund J. Copeland, Mohammad R.Garousi, M.Sami,Shinji Tsujikawa. (2005) What is needed of a tachyon if itis to be the dark energy? Phys.Rev. D71 043003.

Mohammad R. Garousi, M. Sami, Shinji Tsujikawa (2004)Cosmology from Rolling Massive Scalar Field on the anti-D3 Brane of de Sitter Vacua, Phys. Rev. D70 043536.

M. Sami, N. Savchenko, A. Toporensky (2004) Aspectsof Scalar Field Dynamics in Gauss-Bonnet Brane WorldsPhys.Rev. D70 123528.

M. Sami, Alexey Toporensky (2004) Phantom Field andthe Fate of Universe, Mod.Phys.Lett. A19 1509.

Shinji Tsujikawa, M. Sami (2004) A unified approach toscaling solutions in a general cosmological backgroundPhys.Lett. B 603 113

Shinji Tsujikawa, M. Sami, Roy Maartens (2004)Observational constraints on braneworld inflation: theeffect of a Gauss-Bonnet term, Phys. Rev. D70 063525.

Saraykar, R. V. and K. D. Patil (2004) Necessaryconditions for the occurrence of a naked singularity inhigher dimensional dust collapse, Ind. J. Physics, 78,1151.

Sarwe, Sanjay B. and R. V. Saraykar (2004) Non-radialstrong curvature naked singularities in five dimensionalperfect fluid self-similar space-times, Gravitation andCosmology, 10, 1.

Das, H. S., A. K. Sen and C. L. Kaul (2004) The polarimetricEffects of cometary dusts and possible effect of grainaging by sun, A & A, 423, 373.

Singh, G. P., R. V. Deshpande and T. Singh (2004) HigherDimensional Cosmological Model with VariableGravitational ‘Constant’ and Bulk Viscosity in LyraGeometry, Pramana, 63, 937.

Tikekar, Ramesh and V.O. Thomas (2005) A relativisticcore envelope model on pseudospheroidal spacetime,

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Pramana, 64, 5.

Sharma, Suresh, Rohit Dhir, and R. C. Verma (2005)Magnetic Moments of Charmed Baryons using QuarkEffective Mass Scheme, J. Phys. G, 31, 141.

Singh, K. K., and J. P. Vishwakarma (2004) Implosion ofa cylindrical shock wave in a non-homogeneous gas underthe action of an azimuthal magnetic field, Ind. J. Theo.Phys., 52, 161.

Singh, K. K., and J. P. Vishwakarma (2004) Implosion ofa cylindrical shock wave in a non-ideal gas in presence ofan azimuthal magnetic field, Modell. Measure. Cont. B,73, 63.

(b) Proceedings

Ahsan, Zafar (2004) A differential geometric structure onthe space time manifold of general relativity, Proc. 3rdSeminar on Geometry and Topology, (Editor, Sh. Rezapour,Azarbiadjan University, Tarbiat Moallem, Tabriz), 285.

Ahsan, Zafar (2004) Lanczos spin tensor, generalobservers and tetrad formalisms, Proc. 3rd Seminar onGeometry and Topology, (Editor, Sh. Rezapour,Azarbiadjan University, Tarbiat Moallem, Tabriz), 301.

Ambika, G., K. P. Harikrishnan and Kamala Menon(2005) Spatial and temporal Stochastic Resonance inCoupled Map Lattices-. Proceedings of the NationalConference in Nonlinear Systems and Dynamics NCNSD,Aligarh Muslin University, Aligarh, 154.

Goyal, A. K. (2004) Mixed Phase in Compact Stars: M-RRelations and Radial Oscillations Invited GuestContribution in the 1st. Int. Workshop on Astronomyand Relativistic Astrophysics, Olinda, Brazil, Oct. 2003,IJMPD 13, 1197.

Goyal, A. K. (2004) Hybrid Stars Proceedings of IX Int.Symposium on Particles, Strings and Cosmology(PASCOS 2003) Mumbai, Pramana, 62, 753.

Jog, C. J. and C. A. Narayan (2005) Vertical distribution ina galactic disk constrained by a molecular cloud complex,in the Proceedings of ‘The Dusty and MolecularUniverse’, ESA publications: ESA-577, ed. A. Wilson(Noordwijk: ESA), 287.

Kaushal, R. S. (2004) Abstraction and structural analogiesin mathematical sciences, Proc. Int. Conf. on History ofMathematical sciences, ed. by I. Grattan-Guinness andB.S. Yadav, Hindustan Book Agency, New Delhi, 33.

Dwivedi, S., A. C. Pandey and A. K. Mittal (2005) Is therea strange attractor for Antarctic oscillation?, In India and

the Antarctic: Scientific and Geopolitical Perspectives,Eds. S. Chaturvedi, N. Khare, P. C. Pandey, South AsianPublishers, New Delhi, 199.

Pandey, A. C., I. M. L. Das, S. Dwivedi, A. K. Mittal, S.Rai, A. P. Mishra, B. P. Kirtman, V. K. Pandey, A. Mitra, V.Sharma and K. C. Tripathi (2004) Mathematical modellingof certain atmospheric and oceanic phenomenon aroundAntarctica at K. Banerjee center of atmospheric and oceanstudies (KBCAOS): A status review, National Workshopon Indian Antarctic Research – A Status Review,Abstracts, National Centre for Antarctic and OceanResearch, Goa, 89.

Vishwakarma, J. P., and S. Vishwakarma (2004) Analysisof cylindrical imploding shock waves with the rear flow-field isothermal, Proceedings of ISMAMS, 2, 54.

(c) Proceedings (edited)

Iyer, Bala R., V. C. Kuriakose and C.V. Vishveshwara (2004)(eds): Proceedings of the Fifth International Conferenceon Gravitation and Cosmology (Indian Academy ofSciences, Bangalore), 63, 643.

(d) Books

Ahsan, Zafar (Second Edition – 2004, Fourth Printing -July 2004, Fifth Printing - March 2005) DifferentialEquations and Their Applications, Prentice-Hall of India,New Delhi, Bestseller of the years 1999-2004.

Ahsan, Zafar and Nikhat Ahsan (2005) MathematicalMethods, Anamaya Publishers, New Delhi.

Kaushal, R. S. (2003) Measurement and quantumprobabilities, by M.D. Srinivas, University Press,Hyderabad, 2000, Journal of Indian Council ofPhilosophical Research, vol. XX, #3, 243.

Pradhan, A., Shafiullah and S. Narain (2004) A Text Bookon Advanced Calculus; Vandana Prakashan, Gorakhpur.

Verma, R. C. (2004) Computer Simulation in Physics(based on Numerical Methods and FORTRAN),Anamaya Pub., N. Delhi.

(e) Supervision of Theses

Kaushal, R. S. (2004) A study of complex phase spaceapproach to quantum mechanics and supersymmetricquantum mechanics, University of Delhi, Ph. D. Thesis ofA. Parthasarathi.

Pandey, S. K. (2004) Multiwavelength Study of DustProperties in early-type Galaxies, SRTM University,

83

Nanded, Ph.D. thesis of M. K. Patil.

Pradhan, A. (2004) A study on cosmological models ingeneral relativity, V. B. S. Purvanchal University, Jaunpur,Ph. D. thesis of Hare Ram Pandey.

Vishwakarma, J. P. (2004) A study of shock propagationin conducting and non-conducting fluids, D.D.U.Gorakhpur University, Gorakhpur, Ph. D. thesis ofSubhash Vishwak

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(V) PEDAGOGICAL ACTIVITIES

(a) IUCAA-NCRA Graduate School

S. DhurandharMethods of Mathematical Physics I

A. KembhaviElectrodynamics and Radiative Processes IIntroduction to Astronomy and Astrophysics II

R. MisraElectrodynamics and Radiative Pocesses II

T. PadmanabhanMethods of Mathematical Physics IIAspects of Quantum Field Theory (Topical course)

A. N. RamaprakashAstronomical Techniques I

R. SrianandInterstellar mediumGalaxies: Structure, Dynamics and Evolution

T. SouradeepExtragalactic Astronomy I

(b) University of Pune M.Sc. (Physics)

N. DadhichGeneral Relativity

Ranjan GuptaAstronomy and Astrophysics I [Theory (10 lectures)]and Laboratory for III and IV semestercourses (10 sessions and night experiments)

Varun Sahni (jointly with N. Dadhich)Cosmology

K. SubramanianAstronomy and Astrophysics I (about 21 lectures)

M.Sc. (Space Science)

J. BagchiRadio Astronomy (theory classes +experimental sessions)

Ranjan GuptaAstronomy and Astrophysics I (theory) (40 lectures)Advanced Observational Astronomy (Part of thecourse 15 lectures)

(c) Supervision of Projects

J. Bagchi

Vaibhav N. Prakash (Dept. of Atmospheric and SpaceSciences, University of Pune)Relativistic effects in CGCG049-033: a giant, one-sidedjet-like radio source

Satyajit Chavan (Dept. of Physiscs, Swami RamanandTeerth Marathwada University, Nanded)Training in radio astronomy, GMRT observations, AIPS,etc.(long term project 2005-2008).

Aliakbar Dariush (Shiraz University and Arsenjan AzadUniversity, Iran)

The Wolf-Rayet galaxies

Pratik P. Lunavat, Sarvesh B. Devi and G. Ravi Kishore [B.E. (E & TC), Wadia Institute of Technology, Pune]‘Chaparral’ and ‘Cavity-backed Dipole’ feedconstruction for 1400 MHz radio telescope application.

Nikhil Pawar (Dept. of Physics, Fergusson College, Pune)A radio antenna for receiving decametric radio noisefrom Jupiter.

Anupriya Das (Dept. of Physics and Astrophysics, DelhiUniversity)Study of sub-cluster merger in Abell 3376 (VSPprogramme 2004).

Naresh Dadhich

Varghese Anto Chirayath (VSP 2004)Blackholes

Prasun Dutta (VSP 204)Brane world gravity

Vasundhara Vitthal WadekarSwapnil D. GadhaveSonali Ramdas PatilKashmira Suresh PatilSchool Students' Summer Programme (Foucault’sPendulum)

Sanjeev Dhurandharfor a batch of four school students

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Trigonometry: applications to astronomy

Ajit Kembhavi

Anushyam Mohan, JNCASR, Bangalore,Quasars

Ashutosh D., Shreyas N., Priyanka G., Ketan andShipra B.,Veermata Jijabai Technological Institute, Mumbai,Web based user interfaces for astronomical data-sets.

Ranjeev Misra

Reshmi Behra (VSP 2004)Power-spectra of X-ray binaries

Misha Hari and K. Souyma (M.Sc.)Gamma-Ray Bursts

A.N. Ramaprakash

A. Shukla, Pune UniversityPolarization of T-Tauri Stars

A. D. Jayashankar and V. Sharma, GSM EngineeringCollege, Pune, B. Tech.Astronomical observation planning tool

A. Vinodkumar, A. Attupurath and M. BarveVishwakarma Institute of Technology, Pune, B. Tech.RTC and countdown timer

V. S. Shaiju, Mahatma Gandhi University, KeralaCryogenic stepper motors

Vaibhav Karkare (VSP - 2004)Measurement of optical abberations from defocusedimages

T. Padmanabhan

Aseem Paranjpe, St. Xavier’s College, MumbaiIndian Academy of Sciences sponsord Summer ProjectThe gravitational action functional

Prasant Samantray (VSP - 2004)De Sitter Spacetime in different coordinates

R. Srianand

Nidhi Mehta, Physics Dept., Pune UniversityNitrogen abundance in DLAs, (M. Sc project)

Roopa Karmarkar, Wadia College,M. Sc. Project.Distribution of GRBs

K. Subramanian R. Shankar (VSP - 2004)Galactic dynamo

Tarun SouradeepYashar Akrami (M.Sc., Sharif University of Technology,Iran)Primordial perturbations as an observational probe ofinflation

Ehsan Kourkchi (M.Sc., Sharif University ofTechnology, Iran)CMB anisotropy in multiply connected universes

(d) Supervision of Theses

Naresh Dadhich (Guide)Parampreet SinghGravity at High Energies

T. Padmanabhan (Guide)Tirthankar Roy ChoudhuryPhysics of Structre Formation in the Universe

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(VI) COLLOQUIA, SEMINARS,ETC.

(a) Colloquia

G. Rajasekaran: Recent discoveries in neutrinophysics, July 9.

J. Maharana: Unification of fundamental forces,November 4.

G. Madhavan Nair: Indian space programme ,December 27.

Apoorva Patel : Languages of genetic information:Why do living organisms use 4 nucleotide basesand 20 amino acids?, December 31.

Abhay Ashtekar: Black holes in fundamentalphysics, January 5.

Kishore Marathe: Chern-Simons and string theory,January 25.

Anand D. Karve: Don’t let textbooks interfere withyour education, March 14.

(b) Seminars

Firoza Sutaria: The XMM-Newton FOV of M74 andassociated SNe SN2002ap, April 1.

Badri Krishnan: Dynamical horizons and theirproperties, April 13.

Badri Krishnan: Searching for gravitational wavesfrom pulsars using the Hough transform, April 15.

Banibrata Mukhopadhyay: Light-curve due to thehot-spot motion on the neutron star surface, April23.

Dipankar Maitra: XTE observations of the 2003outburst of the microquasar V4641 SQR, June 3.

Sandip Trivedi: An inflationary model in stringtheory, June 7.

Richard Henriksen: What is the dynamic state ofdark matter halos, both young and old?, June 22.

Arnab Rai Choudhuri: Why do millisecond pulsarshave weaker magnetic fields compared to ordinarypulsars?, July 8.

Somak Raychaudhury: The evolution of galaxiesin small groups, July 12.

Srinivas R. Kulkarni: The central engines of gamma-ray bursts, x-ray flashes and supernovae, July 20.

Susmita Chakravorty: Compton drag model forgamma ray bursts, July 30.

Gaurang Y. Mahajan: The Casimir effect, July 30.

Tapan Naskar: Measurement strategies for thepopularization measurement for brown dwarfs,July 30.

Saumyadip Samui: Reionization of the universe,July 30.

Amrit L. Ahuja: Study of pulsar dispersion measure,August 5.

Hum Chand: Probing the cosmological variationof fine-structure constant: Results based on VLT-UVES sample, August 5.

Atul Deep: Near infrared PICNIC imager : Aprogress report, August 5.

Sanjit Mitra: Efficient data analysis strategy forthe de tec t ion o f grav i ta t iona l waves f rominspiraling binaries : Chebyshev interpolation,August 5.

Anand S. Sengupta: Performance of the EHSpipeline on LIGO-S2 data, August 5.

B .S . Sa thyaprakash : Gravi ta t iona l waveobservations : Current status and future prospects,August 10.

Sivarani Thirupathi: Discovery of an L Subdwarfand a lead rich star, August 19.

Vijay Mohan: Search for baryonic dark matter inthe milky way, August 30.

K. Narayan: Closed string tachyon condensation :Orbifold singularities, September 21.

Ujjaini Alam: Is there supernova evidence for darkenergy metamorphosis?, October 11.

Biswaj i t Pandey: Filaments in the universe ,October 12.

Tom Theuns: The intergalactic medium at redshifts2-4, November 16.

Prad ip Kumar Sahu: Signature o f quarkdeconfinement in neutron star, November 25.

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R. Ganapathy: Meteorites and early solar system,December 7.

Ashok Das: Light-front field theories at finitetemperature, December 15.

Nikhil Padmanabhan: The angular galaxy powerspectrum from Z = 0.2 to 0.6 with the SDSS ,December 16.

Pankaj Jain: Is there a preferred direction in theuniverse?, December 23.

Gurbax Lakhina : Relevance o f research onhistorical geomagnetic storms to society, January6.

David Atk inson: Quantum corre la t ions andclassical probability, January 11.

Ashish Mahabal : High-redshi f t quasars andscience with Palomar-quest survey, January 13.

Frank Verhees t : Linear and nonl inear wavephenomena in pair plasmas, January 13.

D. Lynden-Bell: Why accretion disks make jets?,January 20.

E.P.J. van den Heuvel: Evolution of x-ray binaries,January 21.

Banibrata Mukhopadhyay: Hydrodynamic inducedturbulence in accretion disks: Study of energygrowth, January 24.

Sudip Bhattacharyya: Surface atomic spectral linesfrom weakly magnetized rotating neutron stars,January 27.

M. Elvis: Quasar wind: the fourth element, January28.

G. Fabbiano: Chandra observations of merginggalaxies, January 28.

Subhabrata Majumdar: Probing our universe withthe Sunyaev-Zel’dovich effect, February 3.

Swara Ravindranath: Morphological evolution ofgalaxies: Probing the assembly of the Hubblesequence, Feburary 11.

Francis Bernardeau: Mult i - f ie ld inf lat ion(s) ,February 23.

Emmanuel Rollinde: The density structure around

quasars inferred from Lyman-alpha optical depthstatistics, March 24.

(c) Neem Seminars

Parampreet Singh: Discussion on Triality betweeninflation, cyclic and phantom cosmologies, May13.

Sandeep Sahijpal: Some recent results in X-rayflaring and the origin of the solar system, May 14.

Ujjal Debnath: Gravitational dust collapse withcosmological constant, May 27.

Subenoy Chakraborty: The role of anisotropy andinhomogene i ty in Lemat i re -Tolman-Bondicollapse, May 28.

Sanjay K. Pandey: Probing LSS at high redshiftsusing HI emissions, June 7.

S.N. Hasan; From Nbody1 to Nbody6 : The growthof an industry, June 8.

Naresh Dadhich: Probing the universali ty ofgravitation, June 15.

Daksh Lohiya: Softening Deuterium constraints inearly universe cosmology, June 17.

Lalan Prasad: Nanoflares as a plausible coronalheating agent, June 23.

Abhay Ashtekar: The puzzle of information loss,December 30.

(d) IDG Talks

R. Srianand: The z= 10 galaxy: Implications, April2

Amrit Lal Ahuja: Association of coronal massejections with solar flares, April 16.

Ujjaini Alam: Latest results from high redhsiftsupernovae, April 30.

Amir Hajian: Beating cosmic variance, May 7.

Atul Deep: Magnification of type Ia supernovaewith SDSS, September 24.

Anand S. Sengupta: Upper limits on gravitationalwave signals based on loudest events, October 8.

Abhishek Rawat: X-ray properties of Lyman break

88

galaxies in the Great Observatories Origins DeepSurvey, October 29.

Hum Chand: The transverse proximity effect: Aprobe to the env i ronment , an i so t ropy, andmegayear variability of QSOs, November 5.

Sanjit Mitra: Universal limits on computation,November 19.

R. Srianand: A large neutral fraction of cosmichydrogen a b i l l ion year a f ter the b ig bang ,December 3.

Emmanuel Rol l inde: Cosmic s tar formation,reionization, and constraints on global chemicalevolution, December 17.

89

(VII) TALKS AT IUCAAWORKSHOPS OR AT OTHERINSTITUTIONS

(a) Seminars, Colloquia and Lectures

Ujjaini Alam

Is there supernova evidence for dark energymetamorphosis? International Conference on GeneralRelativity and Gravitation (GR-17) Dublin, Ireland, July18-23.

Dark energy deciphering dark energy: Parameterestimation from present and future data, XIII Meetingof the Indian Association for General Relativity andGravitation, Jaipur, December 7-10.

Joydeep Bagchi

Astrophysics of 21 cm hydrogen line, IUCAA-NCRASummer School/VSRP/VSP, May 31 and June 1.

Naresh Dadhich

Universalization as a physical guiding principle, 11thRegional Conference on Mathematical Physics, Institutefor Studies in Theoretical Physics and Mathematics,Tehran, Iran, May 3.

Universalization as a physical guiding principle,University of Kerman, Iran, May 7.

Black holes and Spacetime singularities, IUCAA-NCRASummer School/VSRP/VSP, May 24 and 25.

Probing universality of gravitation, IUCAA, Pune,June 15.

Probing universality (of Gravity) University ofPortsmouth, Portsmouth, United Kingdom, July 13.

Probing Universality (of Gravity) , Queen Mary College,United Kingdom, July 17.

A volume integral quantifier for Anec violations intraversible wormhole spacetimes, InternationalConference on General Relativity, Dublin, Ireland, July20.

Probing universality (of Gravity), University of Oxford,July 24.

Why Einstein? Jamia Millia Islamia, Delhi, August 25.

Probing universality, IUCAA Reference Centre, DelhiUniversity, August 25.

Gravitation, University of Hyderabad, September 5-18.

Thoughts on gravity, Workshop on Strings andCosmology at IUCAA, October 27.

Why Einstein? Workshop on Cosmology, Departmentof Physics, Ramnarain Ruia College, Matunga, Mumbai,November 18.

Why Einstein? University of Allahabad, November 20.

Gravity: Mother of all, Department of Physics, ScottishChurch College, Kolkata, January 3.

Why Einstein? Department of Physics, MangaloreUniversity, Mangalore, January 11.

Gravity: Mother of Forces, National Seminar on Gravityand Light at the Department of Physics, Cochin Universityof Science and Technology, Cochin, January 14.

Universalization as a Physical Guiding , National Seminaron “Gravity and Light”, Department of Physics, CochinUniversity of Science and Technology, Cochin, January15.

Why Einstein? Kumaun University, Nainital, February 21.

A Unified View of the Basic Forces of Nature, KumaunUniversity, Nainital, February 22.

Why Einstein? IIIT, Hyderabad, February 25.

Why There are only Four Basic Forces? Department ofAstronomy, Osmania University, Hyderabad, February26.

Why Einstein? Maharishi Karve Stree ShikshanSanstha’s Cummins College of Engineering for Women,Pune, March 10.

Sanjeev Dhurandhar

Gravitational Wave Observation: The Dawn,Perspectives in particle physics, gravity and cosmologyconference, PRL, Ahmedabad, April 2.

Efficient extraction of inspiral signals frominterferometric noise: Chebyschev interpolation, LSCmeeting, Hanford, US, August 19.

Gravitational Waves: Recent Perspectives, 23rd IAGRGconference, Jaipur, December 7.

Time-Delay Interferometry for LISA, TAMA Symposiumand Winter School, Osaka City University, Osaka, Japan,February 18.

90

Algebraic structures underlying LISA data analysis,Observatoire de la Cote D’Azur, Nice, France, June 10.

The Extended Hierarchical Search for InspiralingBinaries, Caltech, U.S.A., August 31.

Efficient search for inspiraling binary signals usingChebyschev interpolation, Osaka University, Osaka,Japan, February 21.

Ranjan Gupta

Artificial Neural Networks in Astronomy, IUCAA/NCRASummer School VSRP/VSP lecture on May 28.

Use of Small Telescopes and back-end instrumentationfor teaching and research, University of Mauritius, May31.

Recent studies of industrial pollution and its modeling,Dr. Babasaheb Ambedkar Technological University,Lonere, June 14.

Artificial Neural Networks and it’s application toastronomical spectra, B.R. Ambedkar Bihar University,Muzaffarpur, November 1.

Dust models and calculations, Workshop on InterstellarMedium, Bangalore University, Bangalore, December 6-10.

A near-IR stellar spectral library in the H-band usingthe Mt. Abu Telescope, Symposium on Infrared andOptical Astronomy at Mt. Abu Observatory: The pastdecade and the future, December 15-17.

Theoretical modeling efforts of light scattering by non-spherical grains and Plans of a laboratory setup, KobeUniversity, Japan, March 9.

Amir Hajian

Statistical Isotropy of CMB from WMAP Data, Universityof Oxford, UK. March 05.

Rotational Symmetries of CMB Statistics and the Shapeof Our Universe, IPM School on Cosmology and High-zUniverse, Qeshm Island, Persian Gulf, Iran, January 05.

A Bipolar Power Spectrum Analysis of CMB, IAP, Paris,September.

Statistical Isotropy of CMB and the Shape of OurUniverse, ICTP, Trieste, September.

Rotational Symmetries of the CMB Sky, Univ. MilanoBicocca, Milan, September.

Priya Hasan

Near Infrared Photometry of Young Star Clusters, TIFR,Mumbai, May 25

Near Infrared Photometry of Young Star Clusters, MtAbu Symposium, PRL, Ahmedabad, December 16.

Ajit Kembhavi

Virtual Observatories, IIA, Bangalore, April 19.

Virtual Observatories, 11th Regional Conference ofMathematical Physics & IPM Spring Conference, Iran,May 3.

VO tools developed by the VO-I Project, InternationalVirtual Observatory Alliance Interoperability Workshop,Cambridge, USA, May 25.

The VOPlot tools & Software developed by the VO-IProject, International Virtual Observatory AllianceInteroperability Workshop, Cambridge, USA, May 26.

The VOPlot tools & Software developed by the VO-IProject, Johns Hopkins University, SDSS Group, June 1.

Quasars & Super-massive Black Holes, IUCAA-NCRASummer School/VSRP/VSP, June 10 and 11.

Virtual Observatory, Vth Rencontres Du Vietnam on NewViews on the Universe, Vietnam, August 10.

The UGC-Infonet a New Paradigm for the Universities,Dr. Babasaheb Ambedkar Marathwada University,Aurangabad, September 16.

The UGC-Infonet Initiative, Vice-Chancellors' Meet,Margao, Goa, September 25.

Galaxies-near & far, IAGRG Conference & Symposiumon Recent Trends in General Relativity, Cosmology &Astrophysics, Department of Mathematics, University ofRajasthan, Jaipur, December 7.

Lenticular & other galaxies, A Symposium on Infrared& optical Astronomy, Mount Abu Observatory: The PastDecade & the Future at PRL, Ahmedabad, December 15.

The Black Hole at the centre of the Milky Way Galaxy,Jadavpur University, Kolkata, December 22.

Statistics in Astronomy, National Seminar on Statistics inNatural, Social & Biological Sciences, Calcutta University,December 23.

UGC-Infonet Engine, Indo-UK Conference on InformationTechnology on Education and Learning, Le Meredien,

91

Pune, February 17.

Virtual Observatories, Harish-Chandra Research Institute,Allahabad, February 21.

Fundamental Correlations in Galaxies, Harish-ChandraResearch Institute, Allahabad, February 22.

Numerical analysis & software for teachers of commerce& finance, Academic Staff College, University of Mumbai,March 21.

Ranjeev Misra

Radiative Processes and Accretion Disks, ASTROSATWorkshop, BARC, Mumbai. May.

Radiative Processes, Two lectures for Summer School,IUCAA, Pune, June.

The non-linear behavior of GRS 1915+105, Spectra &Timing of Accreting X-Ray Binaries TIFR, Mumbai,January 17-21.

The non-linear behavior of GRS 1915+105, RamanResearch Institute,Bangalore, March.

Accretion disks around black holes, Indian Institute ofScience,Bangalore, March.

Sanjit Mitra

Introduction to Gravity Waves, IUCAA-NCRAIntroductory Summer School on Astronomy andAstrophysics, IUCAA, Pune, June 7.

Universal Limits on Computation, IUCAA-NCRAInformal Discussion Group Meeting, IUCAA, Pune,November 19.

CMB Power Spectrum Estimation using NoncircularBeams, XVI DAE High Energy Physics Symposium, SINP,Kolkata, December 1.

Efficient data analysis strategy for the detection ofGravitational Waves from inspiraling binaries:Chebyshev Interpolation, 23rd Conference of the IAGRG,University of Rajasthan, Jaipur, December 8.

J. V. Narlikar

Impact of physics, chemistry and biology, Guha ResearchConference, Kodaikanal, December 3.

Theory of relativity from a historical perspective, IndianAssociation for General Relativity and Gravitation(IAGRG), Department of Mathematics, University ofRajasthan, Jaipur, December 9.

Special relativity and faster than light motion (Workshopon 100 years of Einstein’s Relativity), IUCAA, Pune,January 2.

Relativity and faster than light motion (a lecture deliveredduring the International Conference organized by theIndian Planetary Society to celebrate the Albert Einstein’sTheories Centenary Year), Mumbai, January 8.

Science as an aid towards value education (NationalSeminar on Philosophy and Science of Value Educationin the Context of Modern India organized by theRamakrishna Mission Institute of Culture), Kolkata,January 22.

T. Padmanabhan

Wild Thoughts on Dark Energy, The Quest for aConcordance Cosmology and Beyond, Institute ofAstronomy, Cambridge, July 6.

Gravity and the Thermodynamics of Horizons, MelbourneUniversity, September 10.

Cosmological Constant - The Weight of the Vacuum,Melbourne University, September 22.

Precision Cosmology - The New Era, Miegunyahfellowship Public Lecture, Melbourne University, October7.

Cosmology - An overview, Workshop on Strings andCosmology, IUCAA, Pune, October 27.

Dark Energy and Cosmology: Overview, DAE Symposiumon High Energy Physics, Saha Institute of NuclearPhysics, Kolkata, December 1.

The quantum vacuum-much ado about nothing,Astronomical Society of India, Nainital, February 22.

A. N. Ramaprakash

Optical Astronomy Techniques : IUCAA-NCRA SummerSchool/ VSRP/VSP June 7 - 9.

Laboratory and Sky Experiments Training : IIUCAA-NCRA Summer School/ VSRP/VSP, June 10.

Varun Sahni

Dark Energy, Workshop on Strings and Cosmology,IUCAA, Pune, India October 27 - Nov 1.

Cosmological Surprises from Braneworld models of DarkEnergy, 14th Workshop on General Relativity andGravitation), Yukawa Institute for Theoretical Physics,

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Kyoto, Japan, Nov 29 - Dec 3.

The mysterious nature of dark energy, 11th RegionalConference on Mathematical Physics, Tehran, Iran, May3-6.

Dark Matter and dark Energy, IUCAA-NCRA SummerSchool/ VSRP/VSP June 10 -11.

Why is the Universe accelerating? Institute of Physics,Federal University of Rio de Janeiro, Brasil August.

M. Sami

Joining the Two Ends, FTAG, Sikkim, February.

Recent Trends in Cosmology, Jamia Millia Islamia, NewDelhi, June 1.

Gauge Invariant Formulation of CosmologicalPerturbations, (workshop on Strings and Cosmology),IUCAA, Pune, October. ( 2 lectures).

Problems and Prospects of Quintessential Inflation, 23rdIAGRG meeting, Jaipur, December.

Quintessential inflation, (workshop on Theoretical highenergy physics, Roorkee (India), March 16 - 20.

Cosmological relevance of scaling solutions, DelhiUniversity, March 18 –19.

Role of accelerated expansion in the dynamical historyof our Universe in the Challenges of theoretical physics,Jamia Millia Islamia, New Delhi, March 16.

Rita Sinha

Cosmological Parameter Estimation - A BayesianApproach, Jamia Millia Islamia, New Delhi, June16.

Cosmological Parameter Estimation for CMBR, IUCAAReference Centre, Physics Department, University ofDelhi, Delhi, July 23.

Monte Carlo Approach in Study of HypernuclearInteractions, Cosmological Parameter Estimation, Schoolof Physical Sciences, Jawaharlal Nehru University (JNU),New Delhi, November 5.

Estimating Cosmological Parameters from CMBR, 23rdIAGRG Conference and Recent Trends in GeneralRelativity, Cosmology and Astrophysics, Jaipur,December 8.

Tarun Souradeep

Statistical isotropy of CMB anisotropy, Japanese

workshop on General Relativity and Gravitation (JGRG-14), Kyoto, Japan, December 1.

Primordial power spectrum from WMAP, Yukawa Institutefor Theoretical Physics, Kyoto, Japan, November 24.

Early Universe from the Cosmic Microwave BackgroundAnisotropy, (review talk at the Strings and Cosmologymeeting) in IUCAA, October 28.Primordial power spectrum from WMAP, (Internationalmeeting COSMO-04), Toronto, Canada, September 17—21,2004.

Statistical Isotropy of CMB maps: A Bipolar SphericalHarmonic analysis, International meeting COSMO-04,Toronto, Canada, September 17—21.

CMB anisotropy from WMAP under scrutiny, TIFR,Mumbai, August 19.

Statistical Isotropy of CMB maps: A Bipolar SH Analysis,20th IAP Colloquium: CMB Physics & Observations,Paris, France, July 2.

Combing the CMB Anisotropy on large scales, CITA,Toronto, Canada, June 21.

Milking the large angle CMB Anisotropy, Departmentof Physics, University of Pennsylvania, June 16.

Statistical Isotropy of the CMB anisotropy, Departmentof Astrophysical Sciences, Princeton University, June 15.

R. Srianand

Do constants vary with time, Colloquium given in IAPParis, June.

Probing the variation of fine-structure constants usingQSO absorption lines, ICTP, Trieste, September.

On the variation of fine-stucture constant, Workshop onStrings and Cosmology, IUCAA, Pune, October.

Physical conditions in proto-galaxies, a talk given in IAUsymposium held in SHAO, Shanghai, China, March 17.

K. Subramanian

Nonlinear restrictions on the galactic dynamo, Leidenworkshop on Magnetic Fields in Galaxies, Leiden, TheNetherlands, July.

Wrapping up summary, Leiden workshop on MagneticFields in Galaxies, Leiden, The Netherlands, July.

Primordial magnetic fields and cosmic microwavebackground anisotropies, Astronomy Colloquium, Max-

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Planck Institute for Radio Astronomy, Bonn, Germany,July.

Magnetic helicity and its flux, Programme onMagnetohydrodynamics of Stellar Interiors Isaac NewtonInstitute for Mathematical Sciences, Cambridge, UK,October.

Primordial magnetic fields and cosmic microwavebackground anisotropies, Institute for Gravitation,University of Portsmouth, UK, November.

Magnetic helicity fluxes in nonlinear turbulent dynamos,Leeds meeting on “Stellar dynamos”, University of Leeds,UK, December.

P. Subramanian

Space weather and Communications, Jagannath Instituteof Technology and Management, Orissa, March 5.

(b) Lecture Courses

S. V. Dhurandhar

General Relativity and Gravitational Waves PhysicsDept., Gauhati University, October 4 - 6 (4 lectures).

Special and General Relativity and Gravitational Waves,Tezpur University, October 7 - 16 (12 lectures)

Ranjan Gupta

Basics of Observations and small telescope: Workshopon Astrophysics for college Teachers and Researchers,Department of Physics, Kumaun University, Nainital,October 25-29. (4 talks)

Ajit Kembhavi

Stellar Structure & Evolution, Workshop onAstrophysics for college Teachers & Researchers,Kumaun University, Nainital, October 25-26. (3 talks)

Galaxies, Workshop on Cosmology, Ramnarain RuiaCollege, Mumbai, November 17-19. ( 3 talks)

Stars - Introduction, Workshop on ObservationalAstronomy with Small Telescopes, V.R. College, Nellore,January 31-February 1. (3 talks)

J. V. Narlikar

Cosmology, Department of Physics, Ramnarain RuiaCollege, Mumbai, November 17-18 (3 lectures).

Relativity and cosmology (the students from the MumbaiUniversity) at IUCAA, Pune, February 14-19 (6 lectures).

Cosmology from the sidelines (lectures to the JuniorResearch Scholars at IUCAA, Pune, March 1, 3, 8, 10, 15(5 lectures).

Cosmology from sidelines, Harish-Chandra ResearchInstitute, Allahabad, March 17, 18, 21, 22 ( 4 lectures)

T. Padmanabhan

Gravitation, IUCAA-NCRA Summer School/ VSRP/VSPMay 19 - 21 (4 lectures)

Varun Sahni

Dark Energy , XIth Brazilian School on Cosmology andGravitation, Mangaratiba, Brazil, July 26-August 4. (4lectures)

R. Srianand

Diffuse matter in space, VSRP/VSP 2004, IUCAA. (5lectures)

K. Subramnaian

Cosmology and structure formation, Summer School/VSRP/ VSP programme, IUCAA. (4 lectures)

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I g i k a o au o C t n V y dInauguration of IUCAA Muktangan Vidnyan Shodhika

The IUCAA Muktangan Vidnyan Shodhika (MVS), the latest offering of IUCAA to the young minds curious about science, wasinaugurated by Professor Yash Pal on June 12, 2004. The exploratorium is intended essentially for school children and will act as a focalpoint for them to have fun with science by actually doing experiments and investigating scientific principles. The exploratory was builtfrom a handsome donation from Smt. Sunitabai Deshpande [wife of Pu.La. Deshpande] and partial funding support from the MarathiNRI organization in the USA called Maharashtra Foundation. The building has been named “Pulastya” (which is the name of one ofthe stars of the Saptarshi constellation), in memory of Pu-La.

The Exploratorium comprises of a small auditorium, where lectures, demonstration of experiments/slide shows, etc. can be held. It alsohas a Laboratory, Computer Centre, and a Library concentrating at present on Astronomy, Physics and Mathematics. On the day of theinauguration, there were lectures by Professor Yash Pal, as well as Professor Dinesh Thakur (University of Michigan) and ProfessorMilind Watve (Garware College, Pune) on the theme of “Fun of Doing Science”.

(VIII) SCIENTIFIC MEETINGS AND OTHER EVENTS

The IUCAA Muktangan Vidnyan Shodhika inaugurated by Professor Yash Pal

Professor Yash Pal in conversation with the students Professor Yash Pal looking through the microscope

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ol St nt me P amSchool Students’ Summer Programmeo S n m al t t e P mSchool Students’ Summer Programme

Since 1993, IUCAA has been conducting summer programme for school students of Pune to give scientifically inclined students, aglimpse on doing science. The programme was conducted for six weeks for students of VIII and IX standards. Each week, a new batchof 30 students was invited to work on a project at IUCAA from Monday to Friday. Groups of four to six students were attached toindividual guides. The programme has no set syllabus or course guidelines. The students and the guide work out their own schedulefor the week. The students were given access to the IUCAA library. On the last day of the programme, that is on Friday, every studentis asked to submit a report on the work carried out during the week.

This year’s School Students Summer Programme was held from April 19 to May 28, 2004. The venue of the programme was the newlyconstructed Pulastya building of Muktangan Vidnayan Shodhika (see the report of its inaugural programme in this issue of Khagol).We try to introduce a new element in this programme when possible. This year the students’ presentation was carried out in the lecturehall of Pulastya. For the students, who gave the presentation, it was their first experience.

Students carried out various projects under the supervision of Amrit L. Ahuja, V. Chellathurai, N. K. Dadhich, Sanjeev Dhurandhar,Arvind Gupta, Ranjan Gupta , T. Padmanabhan, Arvind Paranjpye, A.N. Ramaprakash, Sanjit Mitra, Arvind C. Ranade, R. Srianand,Kandaswamy Subramanian, Prasad Subramanian and Arun V. Thampan.

The Department of Science and Technology sponsored Introductory Summer School on Astronomy and Astrophysics was heldjointly by IUCAA and NCRA from May 17 to June 18, 2004. Thirty five students (final year bachelor and pre-final year masters) ofscience, engineering and mathematics streams from different colleges and universities spread across the country were selected for theschool from an unusually large 350 applications. This year, the summer school also turned international with applications received fromBangladesh and USA. A masters student from Bangladesh University of Science and Technology also attended the school.

During the morning sessions of the school, there were several introductory courses covering topics in astronomy, astrophysics,gravitation, cosmology, etc. which were offered by faculty members of IUCAA and NCRA. The post-lunch sessions were set apart fortalks on exciting areas of research and development in A&A. The speakers of these sessions were drawn from experts in the fields bothfrom the local resource pool, as well as from other institutes in the country. Each school participant was also assigned an academic staffmember of IUCAA/NCRA, with whom (s)he did a reading project. During the last week of the school, all the participants gave 20 minutepresentations on their respective projects.

Facilities like library, internet access, xeroxing, etc. were provided to the students during their stay. A trip was also organized to visit theIUCAA Observatory and GMRT. Additionally, films on space research related subjects were screened during weekends.

The school was coordinated jointly by A. N. Ramaprakash (IUCAA) and D. J. Saikia (NCRA).

I or m ho no d opct um Sc on ro an rIntroductory Summer School on Astronomy and Astrophysics

Participants and Lecturers of the Introductory Summer School on Astronomy and Astrophysics

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Transit of Venus 2004

The rare event of the transit of Venus took place on June 8, 2004.The last transit of Venus from the earth was seen in 1882, nearly122 years ago. Thus, this rare planetary alignment grabbed theattention of members of scientific community, public as well asmedia. IUCAA’s 14 inch, 9 inch and a 6 inch telescopes weretracing the Venus, seen as a small black dot on the disc of theSun. Moving with an angular speed of 3.2 arc minutes per hour,the Venus took about 6.2 hours to cross the disc of the Sun. Thedisc of the Venus made the first contact with the solar disc at10:43:29 hrs and it left the solar disc totally at 16:55:59 hrs. VinayaKulkarni, Madhura Gokhale, Abhra Ray, Hrishikesh Kulkarni, andNilesh Puntambekar recorded a movie of the ingress, black dropeffect, transit and egress using a web camera attached to the 14inch telescope.

ZEE News, Star News, Aaj-Tak, and Sahara television channelsinterviewed A. N. Ramaprakash, Varun Sahni, S.K. Pandey, AjitKembhavi, Vinaya Kulkarni, Abhra Ray (M.Sc. Space Sciencestudent, Pune University), and Nilesh Puntambekar (Sky Watch-ers’ Association, Pune) on the various aspects of the transitphenomenon. The Zee News was giving live telecast of the viewsof IUCAA members and the preparations of the transit viewing atIUCAA for two days prior to the event and also on the day of thetransit. The Star News gave live telecasts of members of IUCAAon the details of the rare phenomenon of the transit on the day ofthe event.

Arrangements were made at IUCAA Science Park area to showthe transit of Venus to the members of public. The solar imagethrough telescope was projected on a screen. Around 1500 peoplevisited IUCAA to view the transit.

Arvind Paranjpye anchored Vigyan Prasar film - Khoj KhagoliyaIkai Ki (in search of astronomical unit) a film on the Transit ofVeus, in which he explained how to and how not to observe thetransit. The film was shot at IUCAA and was directed by DeepakVarma (for Vigyan Prasar). The jury of the CEC-UGC (Consortiumfor Educational Communication and University Grants Commis-sion) festical has awarded the film a citation for best programmefor teachers. CEC-UGC festival is for films/programmes with edu-cational values and they invite entries from organisations andindependent producers.

The various phases of the transit of Venus

During the week, they participated in various common activities.Arvind Gupta conducted a scientific toy making activity for them,Vinaya Kulkarni conducted guided tour of the Science Park andscientific movie appreciation, and Arvind Paranjpye carried out ageneral question answer session, observing spectrum using aspectroscope and coordinated the programme.

Film on Trnsit of venus received citation of best programmefor teachers

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The Vacation Students’ Programme (VSP) for students in their penultimate year of their M.Sc. (Physics) or Engineering degree course,was held during May 17-July 2, 2004. Eight students participated in this programme. The participants attended about 50 lecturesdealing with wide variety of topics in Astronomy and Astrophysics, given by the members of NCRA and IUCAA. Each student alsodid a project with one of the faculty members of IUCAA during this period. The main purpose of this programme is to pre-select theeligible students to Ph.D. Programme. K. Subramanian was the faculty coordinator of this programme.

VV at n S dacation Student n S da acation Studen s rts’ Prs r ts’ Proogroogra m m ea m m e

Participants and Lecturers of the Vacation Students’ Programme

International Virtual Observatory Alliance (IVOA)Interoperability Meeting and Small Projects Meeting

The Interoperability (IO) meeting of the International VirtualObservatory Alliance (IVOA) took place in IUCAA during Sep-tember 27 -29, 2004. The meeting was jointly organised byIUCAA and Persistent Systems Private Limited (PSPL), Pune,who are partners in the Virtual Observatory-India (VO-I) project,which is partially funded by the Ministry of Informationand Communications Technology. The IO meetings are held abouttwice a year in important Virtual Observatory centres in differ-ent countries, and their aim is to provide a platform for discus-sion, planning and collaboration between people working indifferent Virtual Observatories. The Working Groups (WG) of the

IVOA, which were represented in the meeting were Registry,Uniform Content Descriptors, Data Model, Data Access Layer,Virtual Observatory Query Language, Grid and Web servicesand Global Grid Forum. One or more sessions of each WG wereheld during the meeting, with a number of presentations beingmade in each session. There were a small number of plenarytalks, summarizing all the discussions. Working papers emerg-ing from the sessions will be posted on the IVOA website. Thesewill provide directions for further development in the concernedareas.

Speakers getting ready for their talks

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A Small Projects Meeting of the IVOA took place at IUCAAduring September 30 - October 1, 2004, following theInteroperability meeting. The aim of these meetings is to providea forum for the relatively small Virtual Observatory projects in theAsia-Pacific region to discuss the work undertaken by them, theproducts made ready and plans for the future. The first suchmeeting was held in Beijing in November 2003 and the meeting atIUCAA has been the second one in the planned series. The spe-cific aim of the meeting at IUCAA was to bring together Observ-ing Facilities, which have been recently completed or will beready in the near future, and people working on VO relatedprojects. From India, there were presentations on the HimalayaChandra Telescope (HCT), The TAUVEX Mission and projects

undertaken by VO-I. There were also presentations by VO projectsfrom Australia, China and Japan and plenary talks and discus-sion sessions on science from the VO and the progress of VOfrom development to deployment.

A public lecture by Francoise Genova, Observatoire deStrasbourg, Strasbourg was organised at the ChandrashekharAuditorium, IUCAA and another one by Peter Quinn, EuropeanSouthern Observatory, Munich, in the Devang Mehta Audito-rium at PSPL. About fifty astronomers and software engineersfrom abroad, and a similar number from India attended both theIVOA meetings. A.K. Kembhavi was the coordinator of thesemeetings.

Participants of the IVOA meetings

A five-day workshop on “Astrophysics for College Teachers andResearchers” was conducted successfully at the Department ofPhysics., Kumaun University, Nainital, during October 25-29, 2004.It was attended by fourteen teachers and researchers from re-mote parts of Uttaranchal and UP, six from Aryabhatta ResearchInstitute of Observational Sciences (ARIES), and fifteen localparticipants including teachers and researchers from other disci-plines of the Kumaun University.

The Workshop was inaugurated by the Vice Chancellor, R.C. Pantof Kumaun University, Nainital on October 25, 2004. The speak-ers and the topics were as follows:A.K. Kembhavi (IUCAA) on Stellar atmospheres, internal struc-ture, energy balance, and spectra of stars; Ram Sagar (ARIES)on (i) Star clusters with particular reference to galactic clustersand (ii) New technology telescopes; M.C. Pande (ARIES) on Mag-

WW k o n torkshop on Astr p c o o e h s r ophysics for College T er a h eachers and R eesear h schers

netohydrodynamics; L.M. Saha (Zakir Husain College, New Delhi)on Sun and the solar system; Kavita Pandey (Kumaun Univer-sity) on Solar neutrino problem; Suchi Bisht (Kumaun Univer-sity) on Particle physics and how its laws could be applied tothe understanding of universe in a few minutes after the bingbang; Rajmal Jain (PRL) on (i) Dynamic sun, (ii) Instrumentationand (iii) Data analysis of the observations by the SOXS mission;Wahab Uddin (ARIES) on Details of the contribution of ARIESsolar astronomers in observation; Seema Bisht (Kumaun Uni-versity) on Solar flares and prominences; and Ranjan Gupta(IUCAA) on Small telescopes and their back end instrumenta-tion. In addition, Ajit Kembhavi delivered a popular talk on Vir-tual Observatories Data Base.

The coordinators of the workshop were Kavita Pandey (KumaunUniversity) and Ranjan Gupta (IUCAA).

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Participants of the Workshop on Astrophysics for College Teachers and Researchers

Worksh Strin Cosmoop gs logyWorkshop on Strings and Cosmology

An attempt was made to start a dialogue between the practitioners of strings and cosmology through a workshop organised at IUCAAduring October 27 - November 1, 2004. About 25 active workers from either side came together and meeting had good review as well astechnical talks. The format was discussion intensive, as there was enough free time for informal discussions. It was a wonderful andrefreshing experience for the participants. The idea was for cosmologists to open up to developments in quantum gravity as well as forstring theorists to address cosmologically meaningful questions. It was unfortunate that the loops remained under represented,because many of the loopy people were out of the country at that time.

Going by the overall enthusiasm, it has been proposed that such dialogue should continue at a regular frequency. The coordinators ofthe meeting were N.K. Dadhich and M. Sami.

Participants of the Workshop on Strings and Cosmology

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Participants and Lecturers of the Workshop on Observational Astronomy with Small Telescopes

W orkshop on Astronomy with Small Telescopes

A five-day workshop on “Interstellar Medium” was held in theDepartment of Physics, Bangalore University during December6-10, 2004. It was also noted that interestingly, the year 2004 hap-pened to be the centenary year of the discovery of interstellarmedium!

The workshop was inaugurated by the Vice Chancellor of Banga-lore University, M.S. Thimmappa on December 6, 2004. The speak-ers and the topics were as follows:

M.N. Anandaram (Bangalore University) on Review of the essen-tial astrophysical concepts; Jayant Murthy (IIA) on (i) Charac-

on Workshop on Interstellar Medium

teristics of spectral lines and (ii) Analysis of space mission data;D.C.V. Mallik (IIA) on (i) Evidences for ISM and (ii) Heating andcooling processes; K.S. Dwarakanath (RRI) on H21 cm line inthe study of ISM; R. Srianand (IUCAA) on ISM at high redshifts;H.C. Bhatt (IIA) on Dust and star formation in ISM; G. Srinivasan(RRI) on Super novae and their influence on ISM; YashwantGupta (NCRA-TIFR) on The study of ISM through radio as-tronomy; Ranjan Gupta (IUCAA) on Models of dust; C. Sivaram(IIA) on Chemical and biological processes taking place inISM.

The coordinators were: R. Srianand from IUCAA and B.A. Kagalifrom Bangalore University.

Participants and Lecturers of the Workshop on Interstellar Medium

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A five days Workshop on Observational Astronomy with Small Telescopes was held at Department of Physics, V.R. College, Nellore,during January 31 to February 4, 2005. The workshop was inaugurated by Ajit Kembhavi. Speakers and topics were as follows:

Ajit Kembhavi (IUCAA) on Light of Stars; Vijay Mohan (Visiting Scientist, IUCAA) on Data Analysis Techniques in Astronomy; S.K. Pandey (Pt. Ravi Shankar Shukla University, Raipur) on Observational Projects with Small Telescopes and R. Ramakrishna Reddy(S.K. University, Anantapur) on Stellar Spectroscopy.

Vijay Mohan took special sessions on ‘Hands-on Training on Data Analysis’ and Arvind Paranjpye carried on ‘Hands-on Training onPhotoelectric Photometry Observations’ for selected participants and followed by subsequent sessions on data analysis.

There were 33 registered participants, of which 29 were from the different parts of the country.

A. N. Ramaprakash (IUCAA), S.K. Pandey (Pt. Ravi Shankar Shukla University, Raipur), and P. Sudhakara Reddy (V.R. College, Nellore)coordinated the workshop.

A training workshop on High Performance Computing (HPC) was held in IUCAA from Oct.~5-9, 2004. The workshop was a jointventure with members of CDAC Pune. CDAC members conducted the HPC course along the lines of their regular HPC programs andalso made available teaching manpower and the course material. The workshop scheduled many hands-on sessions to allow partici-pant to work on the HPC facilities both at IUCAA and CDAC, Pune round the clock. The workshop also featured inspiring seminars byprominent scientists who use HPC in very different fields. There were talks on upcoming trends like grid computing and of the nearfuture possibilities in HPC. There was a live compute cluster building demonstration by IUCAA associate, Sajeeth Phillip and apresentation by Redhat on available and upcoming linux clustering tools.

The prime motive was to generate users for the HPC facilities in IUCAA and CDAC. There were over 60 participants from all over Indiawho benefited from this workshop. A large number of computers were set up that allowed all participants to work simultaneously.Typically, CDAC training courses are costly and inaccessible to the university sector. Being an IUCAA activity allowed free participa-tion from the University sector. The workshop was successful in creating users from the University sector. This was perhaps the firstserious joint venture between IUCAA and CDAC and strongly appreciated by Directors ofCDAC.

The workshop was coordinated by Tarun Souradeep and IUCAA HPC team members, Sarah Ponthratnam, Rita Sinha, Sunu Engineer,Sanjit Mitra and Anand Sengupta. Dr. Sundar Rajan and Dr. V.C. V. Rao led the CDAC team. Administrative support was provided byManjiri Mahabal & Swati Gujar and system administration team of IUCAA set up and ably managed the large computer laboratory setup for the meeting.

W k o g p orkshop on High P r um terformance Computing

Participants of the Workshop on High Performance Computing

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Public Outreach Programme

Muktangan Vidnyan Shodhika

Three times a week about 50 children from one particular schoolcome to the centre and spend 4 hours making toys that spin, fly,whistle, jump, and hop. They make “action” toys, for all childrenare attracted to dynamic toys. Children learn to fold a dozen dif-ferent caps using old newspapers. They learn geometry by paperfolding making the rotating hexa-flexagon using an old photo-copy paper!

At slightly higher level students of St. Mira’s College for Girls,Reshma Lalwani and Hritul Madge (IInd year Junior College) vis-ited the Exploratorium for two weeks to study and to design aSundial for their college. Priyadarshini S. Bangale, first year stu-dent of Electronics and Telecommunication of MGM CollegeNanded, did a project on The Study of Solar Limb Darkening.Three final year students of Cummins college of Engineering,Pune, Bakul Purohit, Parchee Bahulekar and Sonali Deshmukh,fabricated a Coelostat for the Solar observatory of theExploratorium.

SLt Kanand Bhagwat and Slt Nikhil Kane (trainee officers at theFaculty of Training Project, Electrical Technology School, INSValsura, Jamnagar) did a project on Data logger for photoelectricphotometer.

Space UK Exhibition

A SpaceUK exhibition on the solar system and its exploration,was kept open at IUCAA for the people during August 1- 8, 2004.The exhibition has been commissioned by British Council. TheUnited Kingdom has played an important role in the solar systemmissions, both by developing spacecraft and instrumentation andby interpreting the results. The SpaceUK exhibition highlightedon those missions and the future UK led exploratory missions tothe Moon, a comet, Mars, Venus and Saturn as well.

The exhibition looked at the key missions regarding solar systemexploration and described some of the challenges that scientistsand engineers face in designing a spacecraft. With striking graph-ics and a walk-through tunnel display, SpaceUK delved into thescience behind the missions and the questions that will be an-swered about the planets, comets and asteroids. A scaled downmodel of the solar system hung on a stand gave an idea of com-parative sizes of the planets and the Sun, and the distances in thesolar system.

Everyday, screening of The IUCAA Story, Taryanchi JeevangathaI & II (Life cycle of stars), Powers of Ten was also done one afterthe other during the day time, and during August 2-7 everyevening, a popular talk or a scientific film was arranged at theChandrasekhar Auditorium. Pandit Vidyasagar, from the Depart-ment of Physics, Pune University (Brain: Known and Unknown),Murali Sastry from National Chemical Laboratory (Nanoscienceand the Next Industrial Revolution), and Tarun Souradeep fromIUCAA (Unravelling Our Universe) gave popular talks.

In spite of heavy rains, students, amateurs and enthusiasts turnedup in thousands to view the exhibition. Many of the curious

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students took out their notebooks to take down the informationabout various missions. Apart from the information content, view-ers found the exhibition in the form of tunnel display very impres-sive.

The exhibition was in India till November 2004. It was inaugu-rated at the Goa Science Centre on July12, 2004. After Pune, theexhibition moved on to Mumbai, Vadodara, Gandhinagar, Delhi,Bhopal, Kurukshetra and Kolkata.

National Science Day

The National Science Day was celebrated at IUCAA during Feb-ruary 27-28, 2005. On Sunday, February 27, the Centre was openedto the general public, so that they may acquaint themselves withthe research done at IUCAA and appreciate scientific temper andmethodology. On Monday, the 28th, science related competitions,which were designed to test the exploratory and imaginative skillsof the participants, were held for high school students.

The Open House for Public

A large number of people from all age groups and different pro-fessional backgrounds visited IUCAA on Sunday, February 27.The visitors viewed several posters describing the basics of As-tronomy and Astrophysics and the fundamental research doneat IUCAA. They interacted with IUCAA members who demystifiedthe technical details of the research activities. A kiosk was alsoset up where individuals could ask questions or doubts they mayhave about astronomy, directly to astronomers, like Professor J.V.Narlikar. Short interactive lectures were held in different topicsincluding one about career prospects in Astronomy for thoseaspiring to become Asronomers. A public talk, which explainedthe importance of this year’s Nobel prize in physics, in non-tech-nical language, was presented in the evening. Demonstrations ofhow the atmosphere affects astronomical observations and howRadio Telescopes work were set up as examples of how astro-physical research is undertaken. The visitors were shown how amodel of the robotic Mars explorer, Rover, could be controlled bya computer. Science documentaries on interesting scientific top-ics were shown. Actual samples of meteorites (i.e., rocks fromspace which can be older than the earth) were exhibited.

Visitors were encouraged to get hands on experience of scienceusing several do-it-yourself experiments set up in the recentlyinaugurated Muktangan Vidnyan Shodhika, which is a uniquecentre that facilitates school students to learn about science in afree and fun atmosphere. These experiments were designed andpresented by students of Rewachand Bhojwani School. Students(Kshitija Deshpande, Rohit Belapurkar and Rahul Sangole) fromPune Institute of Engineering and Technology, Maharashtra In-stitute of Technology and Pune Vidyarthi Grihas College of Engi-neering and Technology respectively, displayed an airship whichthey had designed and made. A computer was set up by NIIT,Delhi which allowed people to self learn about computers. A popu-lar place was the IUCAA science park, where there are severalinteractive outdoor exhibits, each one designed to explain a sci-entific principle.

Inter-School Competitions

Several schools were invited to take part in the inter-school sci-ence competitions held on Monday, February 28, at IUCAA. Fiftyfive schools participated by sending a team of five students each.Drawing and Essay competitions were held with topics suitablychosen to enable the students to exhibit their scientific knowl-edge as well as a fertile imagination. Based on a preliminary writ-ten quiz held in the morning, three member teams from five schoolstook part in the final quiz contest. The students were tested fortheir scientific and technology knowledge, as well as their abilityto solve puzzles. The students and their teachers were introducedto the making of scientific toys with common cheap materials,that would enable young minds to learn and be excited aboutscientific inquiry.

A great deal of planning and administration was necessary forthe smooth execution of the celebrations of the National ScienceDay, which was possible because of the active participation byall the members of IUCAA. IUCAA thanks the volunteers fromSky Watchers Association of Pune for helping with the NationalScience Day celebration.

Sky Watch Program

In the evening of Monday 28th, a sky watch programme wasorganized. The IUCAA’s six-inch telescope was used by thepeople to see various aspects of the night sky, including Jupiter,Moon and the Orion Nebula.

Lecture Demonstration

Since 1993 IUCAA has been organizing lecture demonstrationprogramme for the students of class VIII to X. This programmehas been very popular and successful.

During the period of the report, 6 lectures were organised whichwere attended by about 6000 students.

Lectures for High School Students (Classes VIII - X)

[Every speaker delivered lecture in Marathi and then in English]

Arvind ParanjpyeBe an Amateur Scientist, July 10

A. L. AhujaNine Wonderful Planets, August 14

M. PrakashHow to Study Maths Effectively?, October 9

C. K. DesaiElectromagnetic Induction, December 12

Pradeep GothoskarThe Story of Red-Green-Blue, January 8

Jayant NarlikarCosmic Illusions, February 12

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The experiments being explained to the visitors during the National Science Day

The Quiz-winiing team holding the trophy

Students at the Essay Competition

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Drawing Competition

1st Prize: Mayura M. Datar, Jnana Probodhini Prashala, Pune.

2nd Prize: Nikita A. Bhate, Symbiosis Secondary School.

3rd Prize : Soundarya Sunder Pawar, Judson High School.

Honorable Mention

Mayur Valmik Ladkat, Shri Fattechand Jain Vidyalaya.

Meeta Vishwas Kurundkar, Muktangan English School.

Essay Competition (Marathi Medium)

1st Prize : Snehal Nilkanth Chavan, P.E.S. Girls’ High School.

2nd Prize : Vallabh Sanjay Joshi, M. S. S. High School.

Honorable Mention

Nirmitee Vinod Watve, Ahilyadevi High School for Girls.

Essay Competition (English Medium)

1st Prize : Prachi Ashok Joshi, Abhinava Vidyalay English Me-dium School.

No essay was adjudged for the award of second prize.

Honorable Mention

Leah Thomas, St. Joseph High School, Pashan

Quiz Competition

1st Prize

Abhishek Hemantkumar Dang, Aniket Rajendra Inamdar, andKedar Sanjay Jumde from Jnana Prabodhini NavnagarVidyalaya.

2nd Prize

Priya Rajendra Sidhaye, Tanay Milind Deshpande and AdwaitJayant Gandhe from Abhinava Vidyalay English MediumSchool.

3rd Prize

Swetava Tapash Ganguli, Shreyas Ganesh Patankar and AmeyaPramod Phalake from Vidya Bhavan High School.

The following two schools were also qualified for the finalround of the quiz competition.

Kendriya Vidyalaya, Southern Command : Mayur Ghawat,Tarun and Sanjeev Suresh and

N.M.V. High School: Chetan Ajay Doifode, Ameya SushilSavare and Girish Shrinivas Vaidya.

Results of various competitions

Public lectures

Pandit Vidyasagar, Dept. of Physics, Pune UniversityBrain : Known & Unknown, August 2

Murali Sastry, National Chemical Laboratory,Nanoscience and the next industrial revolution, August 5

Tarun SouradeepUnraveling Our Universe, August 6

Peter KalmusThe Forces of Nature, October 8(In association with the British Council, Mumbai)

Roddam NarsimhaA Love of Flow, December 29

Pervez HoodbhoyWhy Scientific Revolution Didn’t Happen in Our Part of theWorld?, January 19(With presiding remarks by Jayant Narlikar)

Special Relativity Centenary Meeting

A one day Lecture series for the undergraduate and junior col-lege students was organized to commemorate the launch of theInternational Year of Physics, on January 2

The speakers and their topics:

Abhay Ashtekar (Director of the Center for GravitationalPhysics and Geometry, Penn State University,USA)Space and Time: From Antiquity to Einstein and Beyond

Donald Lynden-Bell (Professor of Astrophysics at the Univer-sity of Cambridge, UK)The Relativity of Rotation: Before and After Einstein

Gavin Wraith (Emeritus Reader, Department of Mathematics,University of Sussex, UK)Ideas of Space and Observability

Jayant Narlikar (Professor Emeritus, Inter-University Centrefor Astronomy and Astrophysics, India)Special Relativity and Faster than Light Motion

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Ranjan Gupta

Astronomical Observatories — New Telescopes in India andAbroad, Dept. of Physics, Jamia Millia Islamia University, NewDelhi October 26.

Priya Hasan

Galaxies and AGN at a seminar on Women in Science, Birla Plan-etarium, Hyderabad, November 19.

Birth and Life of Stars Aurora College, Hyderabad, December 16.

Ajit Kembhavi

Stars, Summer Camp in Science at Chinmaya Vidyalaya, Hubli,April 21.

The Virtual Observatory, Panjim, Goa, Sept. 23.

Black Holes, M.B. Govt., P.G. College, Haldwani, Oct. 27.

Binary Stars- Astronomy and Physics, Nehru Planetarium,Allahabad, Febuary 22.

Careers in Astronomy & Astrophysics, Science Day, IUCAA,Pune, February 27.

Einstein’s Gravity and Black Holes, Science Day, Agarkar Re-search Institute, Pune, February 28.

J. V. Narlikar

Cosmic illusions (a talk delivered at the Science Festival in Genoa,Italy), November 4

From black clouds to black holes (a talk delivered at the ScienceFestival in Genoa, Italy, ) November 7.

The Culture of Science (C.D. Deshmukh Memorial Lecture deliv-ered at the India International Centre, New Delhi, ) January 14.

Vidnyanprasarachi Garaj (A need of science popularization)(inMarathi) (a lecture organized by the Vidnyanvahini, Pune,) Janu-ary 16.

Modern cosmology from a historical perspective (a lecture deliv-ered under the ‘Bengal Science Lectures’ Series’ organized bythe Government of West Bengal at the Rabindra Sadan Audito-rium, Kolkata, ) January 20.

Cosmic illusions (a lecture delivered on the occasion of the Foun-dation Day of the National Institute of Oceanography, Goa,) Janu-ary 28.

Paragrahavarchi jeevshrusti (Extra-terrestrial life)(in Marathi) (alecture delivered during the Amateur Astronomers’ Meet 2005,Goa,) January 29.

Kya bramhand mein hum akale hein (Are we alone in the uni-verse?) (in Hindi) (Second Baburao Pimpalapure Memorial Lec-ture, Sagar, ) February 5.

Popular Talks and Articles by the IUCAA Faculty

a) Popular Talks

Naresh Dadhich

(2004) Riding on the Shoulders of Giants (a lecture delivered atGorakhpur University), April 19.

Universalization as a Physical Guiding Principle (a general talkdelivered to the science students) Gorakhpur University, April 19

Black Hole and Space-Time Singularities (a lecture delivered tothe VSP students in IUCAA,) May 24

Universality of Gravity, Homi Bhabha Centre for Science Educa-tion, Mumbai, June 14.

Why Einstein? Maharashtra Institute of Technology, Pune, July31.

Why Einstein? Mathematics department of Abasaheb GarwareCollege, Pune, August 17.

Science: Method and Vision, Institution of Electronics and Tele-communication Engineers, Pune, August 30.

From the Shoulders of Giants, Veermata Jijabai Technological In-stitute, Matunga, Mumbai, September 2.

Vaigyanik Drishti Aur Samajik Paripeksha delivered at JawaharPlanetarium, Allahabad, November 19.

Why Einstein?, Motilal Nehru National Institute of Technology,Allahabad, November 20.

From the Shoulders of Giants, students of Central School, Bhopal,November 22.

Science: Method and Vision, Regional Institute of Education,Bhopal, November 22.

From the Shoulders of Giants, students of Central School, Indore,November 23.

Science : Method and Vision Institution of Engineers (India), Pune,November 29).

Why Einstein? International Conference organized by the In-dian Planetary Society to celebrate the Albery Einstein’s theo-ries Centenary Year, Mumbai, January 9.

Why Einstein? B.M. Birla Science Centre, Hyderabad,February 25.

S. V. Dhurandhar

The Story of Gravity, lecture at Darang College, Tejpur on Octo-ber 11.

Gravity, on the occasion of the Science day programme at IUCAA,February 27.

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Badalti duniya mein Hindustan (The role of India in a changingworld)(in Hindi)(a lecture under Aaj Ka Bharat Lecture Series,Bhopal, ) February 7.

Cosmic illusions (a lecture delivered under Saturday Lecture Dem-onstration Porgramme at IUCAA, Pune, ) February 12.

Antaralatil drushtibrahm (Cosmic illusions)(in Marathi) (a lecturedelivered under Saturday Lecture Demonstration Programme atIUCAA,) February 12.

The search for extraterrestrial life (a lecture delivered at theCummins College of Engineering for Women, Pune,) March 11.

Scientific temper and its relevance in modern India (a lecture de-livered at the Deccan College, Pune,) March 11.

Prithvi ke bahar jeevasrishti ki khoj ke prayas (Search for extrater-restrial life)(in Hindi) (a public lecture delivered at the JawaharPlanetarium, Allahabad,) March 19.

T. Padmanabhan

Dark Energy: the Cosmological Challenge of the Millennium, (Sci-ence Day Public Lecture, TIFR, Mumbai), February 28.

Nobel Prize in Physics, (National Chemical Laboratory, Pune),November 5.

Nobel Prize in Physics - 2004, (IUCAA Science Day), February 27.

Understanding our Universe, (Homi Babha Centre for ScienceEducation (HBCSE),Mumbai), December 22.

Special Relativity and Gravity, (International Conference onEinstein’s Theories, The Indian Planetary Society, Mumbai), Janu-ary 8.

A. N. Ramaprakash

Technological Challenges in Astronomy : National TechnologyDay Lecture, May 11.

How far can we see, How faint can we see : SpaceUK Exhibition,Nehru Science Centre, Mumbai, August 17.

Tarun Souradeep

On a cosmic discovery trail?, sponsored by the British Council,Nehru Planetarium, Mumbai, Aug. 18.

Unraveling our Universe, IUCAA, Pune, August 6.

K. Subramanian

Travelling through time, IUCAA Science day, February 27.

b) Popular Articles

Dadhich N. (2004) Indian Science Experiment, (Economic andPolitical Weekly, May 22)

Amir Hajian, “Story of the Creation”, Scientific Magazine of Em-

bassy of Islamic Republic of Iran, New Delhi, April 2004.

Ajit Kembhavi

Electronic Subscriptions for Indian Universities. Informatics News-letter, January 2005. Page 3.

Kembhavi, Ajit, Information and Computer technology for theUniversities. EduComm Asia, Vol 10, No. 2, Page 2.

Kembhavi, Ajit, International year of Physics 2005. In Marathi.daily Sakal (Saptarang), Jan 9, page 5.

J. V. Narlikar

(2004) Creating successful scientific institutions, (Ideas that haveWorked, 99) -

(2004) Science journalism in India and abroad, (Science Reporter,December)

- (2004) Salad days, (Souvenir, 43) (Article published on the occa-sion of the 70th Annual Meeting of the Indian Academy of Sci-ences, Bangalore at the Banaras Hindu University Varanasi.)

- (2005) Beautiful mind : A 100 years since Einstein launchedhimself, (Times of India, January 1)

- (2005) Time-keeping in special relativity, (Virat Surya, January,49)

- (2005) Diaryspeak of how a Puneite became Senior Wrangler inimperial England, (The Indian Express, Pune Newsline, February8)

- (2005) The culture of science, (India International Centre Quar-terly, 156)

- (2004) Ujavya sondecha Ganapati (in Marathi)[Ganesha withright handed trunk], (Marathi Katha : Visave Shatak, 415)

- (2005) Vaidnyanik drustikon (in Marathi)[Scientific outlook],(Vidnyanvahini, 89)

c) Radio/TV Programmes

Naresh Dadhich

IUCAA Sanstha Ek Parichay (in Marathi) - An interview to AllIndia Radio, Pune, in the programme entitled, “BAHURANGIMAHARASHTRA”, June 5

J. V. Narlikar

Akashdarshan, Akashwani, Pune, January 16, February 13, March13, 2005

Interview for Horizon, All India Radio, Kolkata, January 26.

d) Science Popularisation

J. V. Narlikar

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(i) Participation in question-answer programmes on key channelson television.

(ii) Occassional talks and interviews on All India Radio and onTV, listed under (d)

(iii) Writing of popular articles in newspapers and magazines,listed under Popular Articles’.

FACILITIES

(I) Computer Centre

The IUCAA Computer Centre continues to providestate-of-the-art computing facility to users fromIUCAA as well as IUCAA associates and visitorsfrom the universities and institutions in India andabroad.

Increased use of laptop computers and increasein worker mobility have fueled the demand for wire-less networks. Till recently, the technology wasslow, expensive and reserved for mobile situationsor hostile environments where cabling was imprac-tical or impossible. With the maturing of indus-try standards and the deployment of lightweightwireless networking hardware across a broad mar-ket section, wireless technology has come of age. InIUCAA, wireless internet connectivity is availablein several locations including the Computer Cen-tre, Library, Bhaskara III, Conference Hall and A3Seminar Room. The access points from 3 COM areused to provide wireless connectivity. The coverageit offers is 100 meters and the protocol supported is802.11g i.e., 54 Mpbs shared. This facility is beingextensively used during international conferences.

The Cisco Long-Reach Ethernet solutionmeets the demands of high bandwidth applica-tions, while leveraging the existing copper wiringinfrastructures (telephone connections). Using thistechnology, internet connection has been providedto Muktangan Science Exploratorium, TakshashilaVIP flatlets and IUCAA housing colony. The de-vices used are Cisco catalyst 2950 Long-Reach Eth-ernet switches, POTS splitter and CPE (CustomerPremise equipment). This facility offers true eth-ernet connectivity over existing telephone lines. Italso delivers fast, reliable connections without re-curring costs.

Lately, internet users have been increasinglysubjected to email abuses such as viruses, worms,spam and other unwanted email content that havepenetrated Internet. As a preventive measureagainst such email abuses, ERNET, our Inter-net Service Provider (ISP), has provided an emailgateway which uses ”Symantec Mail Security forSMTP” at all its ERNET Centres. This softwarecombines virus protection, spam prevention andcontent filtering for email messages to maintainemail integrity and enhance email security. Apartfrom having the Mail Security software at the ISPlevel, ”openprotect” software is being used to scanemails to check for spam and viruses at daakghar,the IUCAA email server. This is a linux based costeffective server side software, which offers protec-tion against virus, spam and dangerous content.

The Computing facility continues to extendtechnical support to visitors, project students and

associates of IUCAA.

(II) Library and Publications

During the period under review, the IUCAA libraryadded 955 books and 450 bound volumes to its ex-isting collection, thereby, taking the total collectionto 20,037. The library subscribes to 129 journals.

The library is also planning to acquire a cdrommirroring server, which would essentially includeinstructional aids, demonstrations of physics ex-periments, astronomy films, etc. on DVD andVCD format, which would increase the usage ofthe cdrom collection.

The IUCAA library has also benefited in termsof access to additional e-journals published byAmerican Institute of Physics, Institute of Physics,Springer, etc. in Astronomy, Astrophysics andrelated areas. This has been provided by UGCInfonet Consortia programme for e-subscriptions,initiated by INFLIBNET, Ahmedabad, under theguidance of the Chairman, UGC.

The IUCAA library is an active member ofthe Forum for Resource Sharing in Astronomy(FORSA), which comprises of ten institutes inwhich, Astronomy and Astrophysics is a major re-search area. A meeting of the FORSA memberswas organized at the National Centre for Radio As-trophysics (NCRA) library, Pune during July 26-27, 2004. The members presented new initiativestaken up in their workplace and discussed the pos-sibilities of forming consortia for journals publishedby American Institute of Physics/American Physi-cal Society, Nature online, World Scientific, etc.

IUCAA has full-fledged publications depart-ment that uses the latest technology and DTP soft-ware for preparing the artwork and layout of itspublications like the Annual Report, Quarterly bul-letin “Khagol”, Posters, Academic Calendar, Con-ference Proceedings, etc.

(III) Instrumentation Laboratory

Over the last year the laboratory has been sub-stantially involved with the installation of IUCAAtelescope, the details of which are reported as a sep-arate section below. Another main project whichis currently underway in the laboratory is the de-velopment of Near-IR PICNIC Imager (NIPI).

It was reported last year that work was inprogress for testing the attenuation achieved by thebaffle arrangment for UVIT, a payload being builtfor the ASTROSAT mission. This work has pro-gressed considerably now, with a prototype bafflebeing manufactured and tested in the laboratory.Tests for understanding the behaviour of photon-counting CMOS detectors for UVIT also are con-tinuing.

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Another development has been the completionof testing of the USB-based data acquisition systemon Windows platform for the CMOS detector ar-ray controllers. Tests of the Linux version of thisis soon to start. With this technology, data fromthe array controllers can be downloaded to a PCthrough a standard USB port, thereby, eliminatingthe need for solutions depending on frame grabbers,etc.

(IV) The IUCAA Telescope

Electrical integration of the IUCAA telescopestarted in July 2004, with the arrival of a team ofengineers at site from Telescope Technologies Ltd,Liverpool, UK, the manufacturers of the telescope.Installation and testing of the electrical system wascompleted by September, which was followed byinstallation of the top-end assembly which carriesthe secondary mirror and the focussing mechanism.Safety interlock installation and a limited amountof software integration allowed the telescope toachieve movement under pendant control. The pri-mary mirror was then installed in early Decemberand engineering first light through an eyepiece andthe autoguider CCD deployed at field centre wasachieved by December 10, 2004 (see Figures 22 and23).

Further system integration work started inearly January 2005, after the Christmas, New Yearbreak for TTL engineers. Alignment of the tele-scope optics, installation of axis encoders, fine tun-ing of the servo controls for pointing and tracking,integration of the enclosure control system (whichwas developed at IUCAA) with the telecope controlsystem, etc. were carried out during this phase ofthe work. Although by mid-February 2005, consid-erable progress was achieved with system integra-tion, further work was delayed by an unfortunatefailure of the Cassegrain rotation system. This leadto an eight week delay in the installation work whenthe Cassegrain motors were returned to the UK,problem investigated and a solution found. Due tothe onset of monsoon in early June, it is expectedthat the final commissioning of the telescope willoccur only after the weather turns suitable for on-sky tests.

Meanwhile, the primary instrument for thetelescope (IUCAA Faint Object Camera and Spec-trograph - IFOSC) and the calibration unit wastransferred from the laboratory to the observatoryin March 2005. The instrument has been now me-chanically and electrically integrated at the directCassegrain port of the telescope. Initial opticaltests have been carried out and the full commis-sioning of the instrument will be undertaken oncethe telescope is operational.

Details of the development of a second in-

strument for the telescope which works at near-IRwavelengths have been discussed elsewhere in thisreport. A direct imaging CCD camera system isalso being procured, which will be used on one ofthe Cassegrain side ports of the telescope. Thisliquid nitrogen cooled CCD camera will offer thecapability for high spatial sampling observations inthe UBVRI wavelength bands. Initial exploratorywork also has started to identify a suitable secondgeneration instrument for the telescope. A strongcandidate instrument being considered is a near-IRimager cum spectrograph.

The need for having a mirror coating plant hadbeen recognized early on in the project. After de-tailed literature survey and inputs from other ob-servatories, a set of specifications had been arrivedat, for a mirror coating plant for the telescope.Technical proposals received from suppliers are be-ing studied at the time of writing this report. It isplanned to have the mirror coating plant commis-sioned so as to be ready for use by mid 2006.

(V) Virtual Observatory

A virtual observatory (VO) makes possible thestorage of vast quantities of astronomical data,which can be retrieved over the internet and usedby astronomers, wherever they may be located inthe world. Virtual observatories have become indis-pensable tools in a situation where vast quantitiesof data at different wavelengths are produced ev-ery night by major observatories on the Earth andin space. Data obtained at different wavelengthsrequires quite different techniques or analysis andexpertise which takes a long while to develop. How-ever, the modern astronomer needs to take a multiwavelength approach to the study of astronomicalobjects, and it is necessary to have computationaltools and resources for meeting this requirement.

A network of virtual observatories, each withlarge data mirrors in one domain or the other, andtransparent and easy to use tools or analysis, willtherefore, prove to be a great boon to astronomers.With this in mind, virtual observatories have beenset up in several countries over the last few years,and significant progress has been made in develop-ing standards, data formats, query languages andsoftware for analysis, visualization and mining.

The Virtual Observatory-India project is a col-laboration between IUCAA and Persistent SystemsPvt. Ltd. (PSPL), which is a major software de-velopment company in Pune, with expertise in datamining and related areas. The project is funded bythe Ministry of Communication and InformationTechnology (MCIT) and PSPL. The hardware plat-form for the project is located at IUCAA, while thesoftware development is undertaken in close collab-oration at PSPL and IUCAA. VO-I has developed

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Figure 22: Globular cluster M53. Exposure time is 25s, Field is about 225” x 180”, pixel scale is about 0.22”per pixel and the FWHM of stars is about 1.2”

Figure 23: Giant Elliptical Galaxy M87(Virgo A) about 60 Mly away. 240s exposure of the central 220” x180” field. Scale is about 0.22” per pixel. Individual knots in the 8000 light year long optical jet are clearlyseen.

several tools, which have found wide acceptancein the international virtual observatory community,and have been used in making new and exciting sci-entific discoveries, including black holes in galaxiesand rare kinds of stars.

The projects undertaken by VO-I during theperiod of the report are as follows:

1) VOPlot : VOPlot is a 2D/3D plotting and

visualization package, designed for the VOTabledata format, which is a XML based standardfor representing Astronomical Catalogues. VO-Plot supports position plots, histograms, statistics,overlay plots, creating new columns from existingones and a host of other functions. The most strik-ing feature of VOPlot is its ability to interact withother existing astronomical softwares, e.g., Aladin

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(Sky-Atlas). It has been integrated in many As-tronomical Data Archives such as VizieR, HubbleSpace Telescope Archive , OpenSkyQuery Portal.VOPlot lets astronomers do complex plotting, visu-alization and statistics completely online, withouthaving to down load the data, and without havingto issue any commands as VOPlot is completelyevent-driven. It is developed using Java Technolo-gies. VOPlot was developed in collaboration withCentre de Donnes astronomiques de Strasbourg,France. Over the last several months, developmentof 3-D version of VOPlot has been completed, andmuch work has been done in integrating it with thestatistical package VOStat.

2) Data Archival System : The Data ArchivalSystem is designed to archive the data that isgenerated from the Himalayan Chandra Telescope(HCT, Hanle). The telescope observations are out-put as FITS (Flexible Image Transport System)format, a standard for representing images andspectra. The FITS contain a number of headers,which give relevant information about the observa-tion(s). These headers are parsed and then loadedinto a queryable database. The database is acces-sible using a web-based front-end. Users can querythe database for fields such as object name, ob-server, date, etc. The system takes into account dif-ferent users, their privileges, database design, ad-ministrative functions for handling the data, etc. Itis developed using JSP, MySQL Technologies. Thesystem was developed in collaboration with IndianInstitute of Astrophysics (IIA), Bangalore.

3) Streaming and Non-Streaming VOTableParsers : VOTable is a standard adopted by the In-ternational Virtual Observatory Alliance (IVOA).It is a XML (eXtensible Markup Language) basedsystem of representing astronomical catalogue dataas XML offers various advantages in transportingdata over the world wide web. The Streamingand Non-Streaming VOTable Parsers are C++ li-braries, which parse the XML-based VOTable andcarry out raw VOTable processing. This is of im-mense use to the IVOA community and peopleworking on VOTable applications. Libraries areavailable for Windows 95/98/2000/XP and Linuxoperating systems. New versions of the parserswhich are consistent with the latest version ofVOTable have been developed.

4) Data Interface Tool (DIT) : The Data In-terface Tool is designed to create a data retrievaland analysis package for Astronomical Catalogues.It creates an astronomer friendly interface for con-structing a query with various constraints to re-trieve the catalogue-data. The results can then beanalyzed by using VOPlot, retrieving images andspectra from remote image servers using Aladin,SpecView (A spectrum viewer). It is developed us-ing Java and MySQL technologies. A prototype is

ready, and extensive development will be made inthe next phase (VOI-TNG).

A very successful International Virtual Obser-vatory Alliance (IVOA) Interoperability meetingwas organized in IUCAA during September, 2004.The meeting was attended by about 50 participantsfrom abroad and a similar number from India, andwas very useful in setting up new projects and col-laborations. The VO-I team includes Ajit Kemb-havi, Sarah Ponrathnam and Jayant Gupchup atIUCAA, and T.M. Vijayaraman, Amey Navelkar,Sonali Kale, Jagruti Pandya, Nilesh Urunkar andArchis Kulkarni at PSPL. On the scientific side,T. Sivarani, a visitor at IUCAA has used virtualobservatory tools to discover only the third L-typesubdwarf dome in the galaxy using the Sloan sur-vey. C.S. Stalin, who is a post-doctoral fellow onthe VO-I project has been using the tools to findclose pairs of Quasars from the Sloan survey on the2DF survey.

(VI) The IUCAA Radio-PhysicsTraining and Educational Facility

IUCAA is setting up a novel ‘Radio-Physics Train-

ing and Educational Facility’ with technical col-laboration of neighbouring National Center for Ra-dio Astrophysics (NCRA). During 2004-05, signifi-cant progress was made by J. Bagchi and collabo-rators M.R. Sankararaman and M.N. Karthikeyan(NCRA), towards final design of the radio tele-scope, and test and calibration of instruments,meant for this radio astronomy based educationaland training laboratory.The main observational facility will be a 5-meterRadio Telescope for solar (radio-continuum) andgalactic (21cm hydrogen line) observations, whichwill also be used for radio astronomy training work,for the benefit of university students and teachers.All major design parameters were finalised for be-ginning the construction of the radio dish antenna.During phase-I, only one radio dish antenna is to beset-up and its performance would be carefully eval-uated. Subsequently, in phase-II, a second similar(or better) radio telescope would be constructedfor interferometric work. Work has started for set-ting up the first Parabolic dish antenna of 5 meterdiameter.

This should allow observations of Sun, 6.6 GHzMethanol masers, and detection of strong extra-galactic radio sources. This system can also be usedfor SETI experiments (i.e. search for extraterres-trial intelligence) when operated at the 1420.4 MHzspin-flip transition frequency of neutral hydrogen.

They have performed calibration of instru-ments in the GMRT laboratory and also done ac-tual astronomical observations with a prototype 4-

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meter parabolic dish antenna located at the GMRTobservatory. The main aim was to test the perfor-mance of the radio astronomy instruments, demon-strate through sky observations that the requiredsensitivities can be achieved, and use this data asa benchmark for the performance expected fromthe planned 5-meter radio telescope. All these ex-periments were done with an active participationof science and engineering students from Pune andSRTM university, Nanded. A brief summary of theinteresting new results obtained from these labora-tory and astronomical observations are as follows:

• The hydrogen-line spectrometer frequency scalewas calibrated using a precision Rubidium fre-quency standard synchronised with a GPS clock.The 10 MHz master signal derived from the Ru-bidium oscillator was given to the input of a fre-quency synthesiser for generating the exact restfrequency of hydrogen spin-flip transition - i.e.1420.405752 MHz. A correction factor for zero-point shift was derived which was applied for ac-curate frequency/velocity calibration of our 21cmhydrogen line observations of cold galactic neutralhydrogen clouds.

• The hydrogen-line spectrometer temperaturescale was calibrated using observations of severalregions of galactic plane containing IAU recom-mended standard regions. Two standard calibra-tors (S8 in Orion and S7 in Perseus) led to excellentquality 21 cm spectral line observations as shownin the Figure 24. The quality of the 21cm spectralline observations were found to be extremely good.Both sources - one with a simple line profile (S8region), and other having complex multiple lines(S7 region) - could be detected with S/N > 35 in0.3 seconds intergration per channel. Comparisonof the results with much larger, professional gradetelescope observations showed excellent match interm of line-shape, velocity structure and spectralwidth.

• 21cm radio continuum observation of the Sunwere also done. By fast scanning the antenna overthe Sun, many solar traces were obtained. Fromthese traces a value of 3.80 for the half-power BeamWidth (FWHM) of 4-m radio dish was obtained,which is in accord with diffraction theory if oneassumes some degree of illumination taper due tospecific design of the feed-horn. They also obtainedrelative calibration of power level obtained from theSun with a noise-cal diode source injected at theinput of the radio receiver. The antenna tempera-ture provided by the Sun on the observing day was≈ 1366 K.

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R A 05h 47m 21 78sDec −01d 40m 18 22s (J2000)

Figure 24: Upper left: 21cm hydrogen line spectrum showing several blue-shifted lines detected from thedirection of IAU calibrator source S7 in Perseus. The brightest line with peak temperature TB = 90 ± 5 Kand VLSR ≈ −55 km/sec (in blue-shift) is located in the Perseus arm, and the spectral lines near VLSR ≈

-10 to 10 km/sec originate within local arm and other low velocity hydrogen clouds close to Sun. VLSR isvelocity relative to local standard of rest. Couple of lower column density, high velocity clouds in the regionof VLSR ≈ -80 to -120 km/sec originate in sparser outer galactic arms beyond the Perseus arm. Lower left:A schematic drawing of Milky Way depicting this geometry is shown. Upper right: A red-shifted hydrogenline with peak brightness temperature TB = 72 ± 5 K detected from the direction of IAU calibrator sourceS8 in Orion molecular cloud. Lower right: Optical picture of Orion Molecular cloud complex near theBarnard’s Loop which contains hydrogen line standard calibrator source S8. Region S8 is located within thered circle which is approximately the FOV of the 4-m radio telescope used for observation. Data obtainedat the GMRT observatory on 19 April 2005 by radio astronomy students with the IUCAA 21cm hydrogenline spectrometer and 4-m radio telescope.

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functions have, of course, to be determined from experiment of one kind orother.

Such scaling arguments have been used very widely - some times with success,at other times in controversy. They can be seen as simple applications of a kindof group theory, the centre-piece of the argument being a postulate on what therelevant group is.

What engineers often do today is use any tool or method that will help: theoryof course, whenever it is available, testing, computing, simulation, scaling ar­guments and, increasingly, mathematical modelling. This modelling has to bedistinguished from making direct appeal solely to first principles (e.g., Navier­Stokes). Instead, essentially new equations are devised, taking inspiration frombut abandoning equivalence to the Navier-Stokes equations. Ingenuity lies in in­venting equations that give the engineer the reduced information he wants, likethe pipe data of Figure 10. Such models can be at many different levels - fromcodification into charts or tables like Figure 10, through ordinary differentialequations for each flow type (boundary layers, jets, etc.), all the way to systemsof nonlinear partial differential equations (for mean quantities) expected to beuseful for wide classes of flows. Although none of them is spectacularly suc­cessful, many of these models are useful - sufficiently so that there is a minorindustry across the world generating, testing and applying such models to a vastvariety of fluid flow problems - from making better aircraft wings to estimatinghow pollutants disperse to forecasting weather or ocean state.

So I hope, you may see in some small way why some of us love exploring fluidflows: they can be beautiful, crazy, fearsome, important; a challenge whetheryou want to stare at nature's free displays, or visualize flows in the laboratory,or measure them with great precision, or control them so that they do yourbidding; a happy hunting ground if you want to match your skills - of any kind- to try and unravel their secrets and to add to the great deal that is known;but, in essence, still beyond any mathematics or computers invented by man;still out there, so to speak, taunting us to see if we can understand, as we claimto know the basic laws.

If you also feel taunted by those flows, welcome to the fluid dynamicists'club!

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