Interpreting the high-redshift 21-cm signal observations

About 100 million years after the birth of the Universe, the first generation of luminous sources formed. The photons from these sources heated and ionised the gas in the intergalactic medium (IGM). This period is known as the Epoch of Reionization (EoR). Exploring this era will help us understand the “seeds” of the modern-day Universe. The 21-cm signal, produced by the spin-flip transitions in neutral hydrogen, is a unique tracer of the IGM during the EoR. This signal can be found at the radio frequency band. Current radio telescopes have put interesting upper limits on the fluctuations in this signal. In this talk, I will discuss how we can derive physical constraints from the 21-cm signal observations and show what we have learnt from the current observations. In the coming times, the Square Kilometre Array (SKA) telescope will come online, which will be able to produce images of the distribution of the 21-cm signal during reionization. I will also present a forecast study using mock observations of SKA.