Research

Before working as a Management Consultant with McKinsey & Company, I used to work as an Astrophysicist at Harvard University and Tata Institute of Fundamental Research. At Harvard, I was a Junior Fellow of the Society of Fellows and an ITC Fellow at the Center for Astrophysics. I earned a PhD at the Department of Astronomy and Astrophysics, TIFR. Below is a brief account of the topics I worked on.

Background
Massive stars are brilliant but short-lived. They end their lives as supernovae (SNe) within a few millions of years as they exhaust their nuclear fuel within this time. Energetic radiation from associations of these stars ionize the interstellar medium in galaxies and produce localized HII regions as well as diffuse ionized gas. SNe of various types explode from the massive stars that form in these associations which in turn pressurize and churn the interstellar medium. A subset of SNe are also believed to host Long duration Gamma Ray Bursts (LGRBs) which have engine-driven relativistic outflows.

Individual SNe blow bubbles in the interstellar medium and these can be seen for thousands of years as supernova remnants (SNRs). But when many massive stars explode close to each other, they can for much larger and longer lived cavities called supershells. They form and evolve due to the continuous mechanical energy injection by stellar winds and SNe in massive parent OB associations. The outer shocks of the superbubbles sweep up the ambient interstellar medium into a thin cool shell. These supershells may also play a role in triggering the formation of the next generation of stars.

Investigations
A comprehensive description of the feedback processes from SNe, LGRBs, SNRs and supershells would span time scales of a few days to a few million years. A broad understanding may be achieved by systematic observations of a multitude of these events at different stages of evolution and connecting all of them using our theoretical understanding of the underlying physical principles.

We conducted observations of a number of these astrophysical objects. This will entail the use of the Giant Metrewave Radio Telescope (GMRT) operated by TIFR, and other national and international telescope facilities. These multi wavelength observations revealed the nature of non-relativistic outflows from common SNe, relativistic outflows from LGRBs and hitherto unreported subset of SNe. Our comprehensive study constrained their progenitors and the physical processes by which they interact with the circumstellar and interstellar medium. A broad understanding of the feedback processes from these cosmic explosions, both in isolation and in associations, furthers the understanding of their role in energy injection and metal enrichment of the baryonic matter in the universe throughout cosmic history.

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