Astro2020 Science White Paper: Synergies Between Galaxy Surveys and Reionization Measurements

TL;DR

Combining galaxy surveys with reionization measurements offers a comprehensive approach to understanding the early universe's structure formation and the sources responsible for reionization.

Contribution

This white paper advocates for integrated observational strategies combining galaxy surveys and 21-cm measurements to study reionization.

Findings

Synergistic observations can reveal the faint source population.

Optimized surveys require large-volume near-infrared data.

Enhanced 21-cm analysis can improve reionization constraints.

Abstract

The early phases of galaxy formation constitute one of the most exciting frontiers in astrophysics. It is during this era that the first luminous sources reionize the intergalactic medium - the moment when structure formation affects every baryon in the Universe. Here we argue that we will obtain a complete picture of this era by combining observations of galaxies with direct measurements of the reionization process: the former will provide a detailed understanding of bright sources, while the latter will constrain the (substantial) faint source population. We further describe how optimizing the comparison of these two measurements requires near-infrared galaxy surveys covering large volumes and retaining redshift information and also improvements in 21-cm analysis, moving those experiments into the imaging regime.