Imprints of early Universe galaxy formation on the 21-cm signal

Abstract

During the first billion years of our Universe, the first light sources formed. These sources will impact the intergalactic medium, which can be probed using the 21-cm signal. This signal can be found in the radio frequency band and used to study the nature of these first sources. We developed a new semi-analytical framework, ANAXAGORAS, which can accurately model the formation of first galaxies considering all the necessary cooling and feedback processes. We show that presence of molecular hydrogen (H 2 ) is important for forming the first light sources. We further couple ANAXAGORAS with our 21-cm signal modelling code, HMREIO and develop simulations of the 21-cm signal during the era of first sources. We find that the 21-cm signal can constrain the properties of these sources when observed at redshift z 9. During the epoch of reionization, the H 2 cooling becomes inefficient and therefore loses information about the early formation processes.