Studying cosmic reionization with observations of the global 21-cm signal

TL;DR

This paper investigates how observations of the global 21-cm signal can constrain the history of cosmic reionization and properties of ionizing sources, emphasizing model choice impacts and the potential of one-year observations.

Contribution

It compares toy and structure formation models for reionization, showing the importance of model accuracy and the feasibility of constraining reionization with upcoming observations.

Findings

Detection of the 21-cm signal is feasible with sensitive experiments.

Model choice affects the accuracy of reionization history reconstruction.

One-year observations can distinguish between different reionization models.

Abstract

We explore the ability of observations of the global brightness temperature of the 21-cm signal to constrain the reionization history and the properties of the ionizing sources. In order to describe the reionization signal, we employ either a commonly-used toy model or a structure formation model that parameterizes the properties of the ionizing sources. If the structure formation model captures the actual evolution of the reionization signal, then detecting the signal is somewhat easier than it would be for the toy model; using the toy model in this case also leads to systematic errors in reconstructing the reionization history, though a sufficiently sensitive experiment should be able to distinguish between the two models. We show that under optimistic assumptions regarding systematic noise and foreground removal, one-year observations of the global 21-cm spectrum should be able to detect a wide range of realistic models and measure the main features of the reionization history while constraining the key properties of the ionizing sources.