A Short Introduction to Reionization Physics

Abstract

The epoch of reionization probes the state of our universe when the very first stars formed and ionized the hydrogen atoms in the surrounding medium. Since the epoch has not yet been probed observationally, it is often called the "final frontier" of observational cosmology. This final frontier is attracting a lot of attention because of the availability of a large number of telescopes in a wide variety of wavebands. This review article summarizes some of the concepts required to understand the interesting physics of reionization and how to analyze the high-redshift universe using related observations.

Modelling the star-formation activity and ionizing properties of high-redshift galaxies

“…Such studies have yielded crucial insights into various facets of galaxies across different cosmic epochs; for example, their mass assembly histories, the properties of their constituent stellar and black-hole populations, their sizes and structural morphology, their gas and metal contents, and more. These frameworks have even been employed for studying how the formation of the first stars and galaxies initiated a major phase transition of the Universe [22][23][24][25], known as the Epoch of Reionization [2,[26][27][28]. However, our limited understanding of the properties of these earliest luminous sources makes it difficult to accurately reconstruct the ionization and thermal history of the intergalactic medium (IGM) during this transition.…”