SKA India Science working group on

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The SKA India science working group on "Cosmic Reionization & Cosmology" is one of the eight science working groups formed by the SKA India consortium. The group comprises faculty members, post-doctorates, and Ph.D. students from various institutions in India and abroad (with an Indian connection). 

The group's primary focus is on investigating the era when the first luminous sources—stars, galaxies, and quasars—formed, transforming the evolution of the universe. This critical phase, marked by the emergence of these first sources of light, is often referred to as the "cosmic dawn," marking the end of the "dark ages." The subsequent era, during which neutral hydrogen (HI) was ionized by this new radiation, is known as the "cosmic reionization" period, followed by a "post-reionization" phase, where only trace amounts of neutral hydrogen persisted. However, our knowledge of these epochs is limited, with major questions about the timing, properties of the first sources, and their impact on large-scale cosmic structure remaining unanswered. This scarcity of information arises because the signals from this time are extraordinarily faint, making them challenging to observe even with today’s most sensitive instruments.

Neutral hydrogen's 21-cm radiation holds tremendous potential for probing this formative period. The group engages in advanced modeling of the HI 21-cm signal using numerical simulations and develops innovative detection strategies that address the complexities of real-world signal detection. Currently, the group is using the uGMRT to study the challenges of detecting the cosmological HI 21-cm signal and to devise mitigation strategies. The ultimate objective is to enable the detection of this signal with the Square Kilometer Array (SKA), unlocking new insights into the universe's early evolution.