Department of Physics

Indian Institute Of Technology Madras , Chennai

Observing the mysterious Epoch of Reionization using the 21 cm line

Speaker : Dr Suman Majumdar, Astrophysics Group, Imperial College, London, U.K.


Abstract :

A large fraction of the history of our universe is almost unknown till today. So far, we have very detailed observations of the `oldest' light (Cosmic Microwave Background Radiation -- CMBR) that it is possible to see in our universe and we have also managed to get a decent understanding of how the different galaxies are distributed at the present time. A very interesting but largely unknown chapter in this history concerns the period when the first luminous objects were formed in our universe and they radiated energetic photons, which eventually heated and ionized the neutral matter (mostly hydrogen) present in their surrounding inter galactic medium. This particular stage, when our universe was going through a gradual phase transition from being neutral to almost ionized, is known as the Epoch of Reionization (EoR). Detailed observations and understanding of this phase will provide us the missing link between the very early stage of our universe (observed through the CMBR) and the structures observed at present (distribution of galaxies) around us. The 21 cm line - originating as a result of the hyperfine transition in the hydrogen atom - provides us with an unique opportunity to directly observe this epoch. Many radio telescopes, those currently operating (such as the GMRT, MWA, PAPER, LOFAR etc) and those in development (such as the SKA and HERA), aim to observe the EoR via this 21 cm signal. Once detected, it will be important to understand the properties of this signal to properly interpret the physical processes that took place during this epoch. In this talk, I will discuss some of the possible ways to understand and interpret this signal from the EoR using analytical models and numerical simulations.

Key Speaker Dr Suman Majumdar, Astrophysics Group, Imperial College, London, U.K.
Guests None
Place Conference Room
Start Time 3:00 PM
Finish Time 4:00 PM
External Link None