What I Do?
Course Title: Introduction to Astrophysics (PH6120): [Semester 1: February-May 2021]
Conducting laboratory sessions:
Engineering Physics students [Semester 1 and 2 - 2021]
As a professional Astronomer,
I work on observations using ground and space-based telescopes in Optical, UltraViolet, X-ray and Gamma-ray bands. Using various tools on spectral and timing analysis and numerical simulation, I try to understand what happens to the matter close to the black hole before they disappear into it. My research includes data from both stellar-mass black hole (up to few tens of solar mass) in our Milkyway Galaxy as well as supermassive black holes (few tens of million solar mass) residing at the centre of galaxies, billions of miles away from us.
I am working as an instrumental team member (LAXPC) of the AstroSat mission, India's first multi-wavelength astronomical space mission by ISRO, TIFR, IUCAA, IIA, in collaboration with the University of Leicester, UK and the Canadian Space Agency, Canada.
Involved as an International Science Development Team member, Thirty Meter Telescope International Observatory, Caltech, USA, in collaboration with India, China and Japan.
Black Hole Astrophysics: probing extreme gravity with black hole X-ray echos
The inner 30 light-minute radii of accreting supermassive black holes are revealed mostly in UV and X-rays. Among few fascinating events we observe using UV/X-ray satellites, X-ray reverberation is one where X-ray flashes occurred in a region as close as ten light-minutes away from the supermassive black hole and reflected in the accretion disc before reaching the observer. However, such an echoed light is delayed due to bending caused by the extreme gravity of the black hole.
Due to a dramatic breakthrough in developing a fully relativistic, time-dependent, ray-tracing disc reflection model, a more realistic quantitative analysis of X-ray reverberation is now possible. In this project, we compute the delay between the direct and reflected light as a function photon energy, model the X-ray spectrum and use the fitted parameter to perform simulation that agrees with the observed energy-dependent delay spectra.
Outflows from black hole systems : Radio jets and winds
We still have only a very limited understanding of the origin of the relativistic radio-emitting jet, leaving the black hole accretion disc perpendicularly at a speed close to the speed of light. Signature of massive outflows in the form of a strong wind is also evident. The supply for the radio jet and wind comes from X-ray emitting accreting material, but exactly how? Answering questions about this is essential for understanding the energy budget very close to the event horizon.
We are using observations from two most powerful telescopes in the world: Chandra X-ray observatory and e-MERLIN radio telescope, to find out very detailed radio/X-ray connections in a large sample of black hole X-ray binaries