Welcome to our group website.

The 21-cm Cosmology Group (Cosmic Dawn, EoR and Post-EoR) in India is an assembly of faculty members, post-doctorates and Ph.D. students from various institutes and universities in India and abroad (with an Indian connection). The group aims to understand the early universe- particularly the time when the sources of light such as stars, galaxies, quasars etc. appeared first time and completely changed the way the Universe evolved.

The birth of first stars, galaxies, quasars is one of the landmark events in the history of the universe. It is believed that light produced by these sources spread through out the universe and changed its thermal and ionization state completely. The onset of first sources of light which marked the end of the ‘dark ages’ is often termed as ‘cosmic dawn’. Subsequent period when the neutral hydrogen (HI) was ionized is popularly known as the 'cosmic reionization'. The episode after that when a tiny amount of neutral hydrogen survived is known as the 'post- reionization' era. Unfortunately, we have very little knowledge about these period of the universe. Many important questions such as the exact timing, properties of the first sources, impact of this event on the structure formation of the Universe, large scale structure during the post-EoR are largely unknown. This is because the signal coming from this epoch is so faint that even the most sensitive instrument existing could only provide limited information of the event.

Observations of neutral Hydrogen (HI) through its 21-cm radiation is believed to be one of the most promising tools for understanding the landmark episode of the Universe. The group involves in proper modelling of HI 21-cm signal through numerical simulations, devising state-of-the-art detection strategies considering all real life issues in detecting the signal, and real observations with the India based radio telescope uGMRT with the ultimate goal to detect the HI 21-cm signal. The group has also joined the global initiative to build the most powerful radio telescope i.e. the Square Kilometre Array (SKA) through India's active participation in the experiment and shed light on the "Dark Ages, Cosmic Dawn and Reionization epoch".