Aditya Chowdhury

Research Scholar
Email: chowdhury [at] ncra.tifr.res.in
Phone: +91 - 20 - 25719458
Extn: 9458
Office: F250
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA


Main Research Areas: 21cm Cosmology; Atomic Hydrogen in High Redshift Galaxies; Cosmic Dawn;

Supervisor: Jayaram N. Chengalur

Biography:

Aditya obtained his B.Sc. from St. Xavier's College, Kolkata, in 2015. While at St. Xavier's College, he did his final year project on constraining the Hubble constant and the dark matter density using supernovae data from multiple sources. He joined NCRA-TIFR as an Integrated Ph.D. scholar in the same year. He completed the NCRA-TIFR Graduate School requirements in 2018, and is now working with Jayaram Chengalur for his doctoral research.

Research description:

Atomic Hydrogen in High Redshift Galaxies
Atomic gas plays an important role in galaxy evolution over cosmic time by regulating star formation in galaxies. It is now well established that 6 to 10 billion years ago, galaxies formed ten times more stars per year than they do today in the local Universe. However, we know little about the neutral gas in these galaxies which fuelled the high star formation. Aditya is currently conducting a very sensitive search for HI 21cm emission from star-forming galaxies at high redshifts with the upgraded Giant Metrewave Radio Telescope to address this issue, aiming to find out, for the first time, how much atomic hydrogen is present in galaxies at the peak of cosmic star formation. These observations will contribute to an understanding of atomic gas in galaxies and its connection to the star formation history over the past 9 billion years.
Cosmic Dawn
The first stars and galaxies in the Universe were formed approximately 200 million years after the Big Bang. This "lighting up" of the Universe with luminous sources, the epoch of Cosmic Dawn, initiated a phase transition in which the intergalactic medium was ionized. Such a process has been long predicted to leave an observable feature in the HI 21-cm transition of atomic hydrogen which can then be used to understand the formation of these first stars and galaxies. There was recently a tentative detection of this signal using the EDGES telescope in Australia. The observed signal has significant concerns and would require independent confirmation(s) before it can be reliably used for scientific interpretation. A radio interferometer like the GMRT can detect the global signal from the epoch of Cosmic Dawn by measuring the moon's temperature against the background sky. Aditya is contributing to the development and testing of appropriate instrumentation & techniques to conduct this experiment using the GMRT.

Selected publications:

1. Angular momentum content in gas-rich dwarf galaxies (A. Chowdhury  & J. N. Chengalur 2017,  MNRAS, 467, 3856)

2. The Dielectric Breakdown Model applied to explain various morphologies of deposited metallic structures in thin gap metal electro-deposition. (A. Chowdhury & D. Dutta 2015, AIP Advances, 5, 067120)
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