Effect of the cosmological transition to metal-enriched star-formation on the hydrogen 21-cm signal

TL;DR

This paper develops a semi-analytical model to study how the transition from primordial to metal-enriched star formation affects the hydrogen 21-cm signal during Cosmic Dawn, revealing that delay times significantly influence the signal's features.

Contribution

It introduces a flexible model incorporating variable delay times for metal-enriched star formation transition, linking star formation processes to observable 21-cm signals.

Findings

Delay times strongly influence the transition redshift.

Transition imprint affects the 21-cm signal.

Future observations can constrain early star formation properties.

Abstract

Mapping Cosmic Dawn with 21-cm tomography offers an exciting new window into the era of primordial star formation. However, self-consistent implementation of both the process of star formation and the related 21-cm signal is challenging, due to the multi-scale nature of the problem. In this study, we develop a flexible semi-analytical model to follow the formation of the first stars and the process of gradual transition from primordial to metal-enriched star formation. For this transition we use different in scenarios with varying time-delays (or recovery times) between the first supernovae and the formation of the second generation of stars. We use recovery times between 10 and 100\,Myr and find that these delays have a strong impact on the redshift at which the transition to metal-enriched star formation occurs. We then explore the effect of this transition on the 21-cm signal and find that the recovery time has a distinctive imprint in the signal. Together with an improved understanding of how this time-delay relates to the properties of Population~III stars, future 21-cm observations can give independent constraints on the earliest epoch of star formation.