Probing Early Universe using the uGMRT: a case study with ELAIS-N1 observations at Band2

Abstract

Detection of 21-cm signal of neutral hydrogen in high redshift is one of the promising probe to study the physical processes in the early universe, from the Cosmic Dawn (CD) to the Epoch of Reionization (EoR). The domination of foregrounds (bright or diffuse) in the radio sky at low-frequency presents a significant challenge. Aside from foregrounds, there are additional obstacles which include ionospheric corruption, radio frequency interference (RFI), and instrumental systematics. Here, we are presenting radio continuum image from first upgraded Giant meterwave Radio Telescope (uGMRT) observations of the ELAIS-N1 field within the band-2, corresponds to the redshift range of 4.7-10.8. A significant feat is achieved with substantial 32-hour observations and a usable bandwidth of approximately 100 MHz. The final image reached an RMS noise level of 236 µJy/beam, the deepest image so far in this band of uGMRT. © The Author(s), 2026. Published by Cambridge University Press on behalf of The International Astronomical Union.