21-cm cosmology

TL;DR

This paper reviews how 21 cm line observations can unveil the early Universe's history, discussing physics, upcoming experiments, and potential insights into the formation of the first cosmic structures.

Contribution

It provides a comprehensive overview of 21 cm cosmology, including physics, observational strategies, and prospects for future discoveries, with a focus on upcoming radio telescope data.

Findings

Summarizes the physics of the 21 cm signal

Describes upcoming radio telescope experiments

Explores potential insights into early Universe formation

Abstract

Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window into this epoch. This would transform our understanding of the formation of the first stars and galaxies and of the thermal history of the Universe. A new generation of radio telescopes is being constructed for this purpose with the first results starting to trickle in. In this review, we detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations. We also generalize our discussion to intensity mapping of other atomic and molecular lines.