Dr. Sudip Bhattacharyya
    Associate Professor
   Department of Astronomy and Astrophysics (DAA)
    Tata Institute of Fundamental Research (TIFR)
    1 Homi Bhabha Road, Colaba, Mumbai 400005, India

     E-mail: sudip@tifr.res.in 
     Tel: +91 (022) 2278 2925
     Fax: +91 (022) 2280 4610, +91 (022) 2280 4611

Current News
Ph.D. and postdoctoral positions are available.
Upcoming event: I am the Main Scientific Organizer of 42nd COSPAR Scientific Assembly (Pasadena, CA, United States, 14 - 22 July 2018): Scientific Event E1.3 on Millisecond Pulsars.
Recent research in news:
Neutron stars may be emitting gravitational waves continuously.
Recent research in news:
Can we see a singularity, the most extreme object in the universe?

Click on the items below

Home

NASA Award

Press Releases

Appointments/Education

Publications (ADS and arXiv)
(Note: some papers of these lists are by other authors with similar names)


Recent Invited and Plenary Talks

Professional Membership

Useful AstroSat Websites


My involvement in large astronomy observatories

AstroSat
India's first dedicated astronomy satellite

Main responsibilities:

(1) In charge of the Soft X-ray Telescope (SXT) Payload Operation    
      Centre (POC) at DAA, TIFR.
(2) The member-secretary of the AstroSat Science Working Group
.
(3) A member of the AstroSat Time Allocation Committee.

Square Kilometre Array (SKA)
The world's largest radio telescope

Main responsibilities:


(1) A member of the SKA-India Consortium Executive Council.
(2) A co-ordinator of the SKA-India "Pulsar" Science Working
      Group.

(3)
A member of the SKA-India "Transients" Science Working
      Group.


The enhanced X-ray Timing and Polarimetry mission (eXTP)
A future large X-ray astronomy satellite

Main responsibilities:

(1) A member of the eXTP Consortium.
(2) A member of the four Science Working Groups (Dense Matter,
      Strong Field Gravity, Observatory Science, Synergy with GWs) of
      eXTP.



Athena (Advanced Telescope for High ENergy Astrophysics)
A future large X-ray astronomy satellite

Main responsibility:

A member of the "End points of stellar evolution" Science Working Group of Athena.

Thirty Meter Telescope (TMT)
A future large optical telescope

Main responsibility:

(1) A member of the TIFR team contributing to the TMT.
(2) A member of the TMT "Time Domain Science" International Science Development Team.




My main research topics

(1) Properties and evolution of millisecond pulsars and continuous gravitational radiation from them.

Spinning neutron stars, including millisecond pulsars, can emit gravitational waves, if they have a slight ellipticity (popularly known as "mountain") in structure (see here). But so far such continuous gravitational radiation has not been detected.

We have recently shown that some millisecond pulsars could emit gravitational waves. This is because their spin frequencies are expected to be generally much higher than those observed, and it is the spin-down torque due to gravitational radiation that can limit these spin frequencies within the observed limit. See the figure below.

(See also news and the research paper.)


This is one main topic I am currently working on.

(2) Extreme aspects of neutron stars and black holes using X-ray satellite data

I have been working on various X-ray observational aspects of accreting neutron stars and black holes.
X-rays originated from close to these objects provide a unique opportunity to probe strong gravity, superdense matter and some other fundamental aspects of physics.
Some of the X-ray features, that I study, include broad relativistic spectral iron emission line, thermonuclear X-ray bursts, high-frequency quasi-periodic oscillations, etc.

(See news and the research paper on thermonuclear bursts.)

We, for the first time, reported relativistic spectral line from a neutron star source, which opened up new ways to probe strong gravity and superdense matter.

(See news and the research paper.)


Below is our figure of the first reported relativistic spectral line from a neutron star. The clearly asymmetric line profile is well described with a relativistic model (see here).


These aspects of X-ray astronomy are another main topic I am currently working on. I use AstroSat and other satellite data for this purpose.

(3) Numerical computation of rapidly spinning neutron star structures

Another topic I have been working on for many years is the numerical computation of structures of rapidly spinning neutron stars, including the full effects of general relativity (see a recent paper here).
This can be useful to constrain the theoretically proposed equation of state models of neutron star cores (which is a fundamental problem of physics, but cannot be solved in terrestrial laboratories) and to probe neutron star evolution (see here).

(4) Study of a tilted inner accretion disk

A tilted accretion disk around a spinning black hole provides a unique opportunity to probe the strong gravity regime via observable X-ray timing and spectral features.

Recently we have argued that the inner part of a geometrically thin disk could be tilted (contrary to the common belief). This would provide a new way to probe the strong gravity regime (see here).

This is another topic I am currently working on.

(5) Naked singularities and black holes

I am also working on theoretical aspects and the corresponding observational implications of naked singularities and black holes.

Recently, we have proposed a new way to distinguish between a naked singularity and a black hole.

(See news and the research paper.)