INTER-UNIVERSITY  CENTRE  FOR  ASTRONOMY  AND  ASTROPHYSICS
(An Autonomous Institution of the University Grants Commission)

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  SEMINAR

 

Dr. Rajesh Mondal

Stockholm University
 
Probing the early Universe using cosmological 21-cm signal
 
 

The first billion years of cosmic history of the Universe mark the formation of the first stars and galaxies. The appearance of these first sources of light set in motion many lasting changes, which is referred to as Cosmic Dawn (CD). Perhaps the most important one was the transition of essentially all normal matter in the Universe from a cold and atomic state to a hot and ionized one, an event known as Epoch of Reionization (EoR). These epochs hold the key to unlocking many of the remaining mysteries in astrophysics, cosmology and physics. However, as yet, there is very limited observational information available in this field of research. Fortunately, this is currently at the forefront of international cosmological research, and groundbreaking international projects that span the electromagnetic spectrum are soon to come online, e.g. SKA, HERA, REACH, JWST, TMT, LSST, etc. The wealth of data from these experiments will address the following fundamental questions: How did the first cosmic structures form and evolve? When and where were the first stars and Galaxies born? What were the nature and the exact role of the first sources of ionization? What was the role of Dark Matter at early times? One observational probe which can answer most questions related to reionization is a radio signal produced by neutral atomic hydrogen in the Universe, with the rest-frame wavelength of about 21 cm. Due to the expansion of the Universe, signals from earlier times reach us at longer wavelengths. However, to discover what happened during reionization, we need to `model' this signal very accurately, and `decode' the signals in terms of model parameters which describe the cosmology and astrophysical processes. In this talk, I will discuss some of my current research works in this field of research.

 
Online Seminar
January 21, 2021, 15:00 hrs.