Inferring population III star properties from the 21-cm global signal

TL;DR

This paper explores how future 21-cm global signal observations can constrain properties of the first stars, such as their mass and star formation efficiency, using semi-numerical simulations and Fisher analysis.

Contribution

It introduces a method combining semi-numerical simulations and Fisher analysis to predict constraints on first-star properties from 21-cm signals.

Findings

Future observations could significantly constrain first-star mass and efficiency.

Simulations include effects of ionizing photon escape fraction and heating structures.

Fisher analysis accounts for foreground emissions in the constraints.

Abstract

Investigating the properties of the first stars in the universe is essential, yet it remains an open question. One way to explore these stars is by examining their effects on the surrounding gas during the epoch of reionization. In this study, we investigate whether the 21-cm global signal can constrain the typical mass and star formation efficiency of first-generation stars. We perform semi-numerical simulations that include the escape fraction of ionizing photons, which depends on stellar and halo masses, as well as the heating structure surrounding a halo that hosts the first star, determined by radiation hydrodynamics (RHD) simulations. By applying Fisher analysis, while accounting for foreground emissions, we demonstrate that future observations with instruments such as the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) could provide meaningful constraints on these properties.