Effects of feedback-free starburst galaxies on the 21-cm signal and reionization history

TL;DR

This paper investigates how feedback-free starburst galaxies influence the 21-cm signal and reionization, highlighting their potential detectability with future radio observations and their limited impact on hydrogen ionization.

Contribution

It models the impact of feedback-free starbursts on 21-cm signals and forecasts their detectability with next-generation experiments, considering various star formation scenarios.

Findings

FFBs modify brightness temperature and power spectrum evolution.

Limited effect of FFBs on hydrogen neutral fraction.

Potential for significant detection with HERA if popII stars dominate.

Abstract

Different star-formation models at Cosmic Dawn produce detectable signatures in the observables of upcoming 21-cm experiments. In this work, we consider the physical scenario of feedback-free starbursts (FFB), according to which the star-formation efficiency (SFE) is enhanced in sufficiently massive halos at early enough times, thus explaining the indication from the James Webb Space Telescope for an excess of bright galaxies at $z \geq 10$. We model the contribution of FFBs to popII SFE and compute the impact these have on the 21-cm global signal and power spectrum. We show that FFBs affect the evolution of the brightness temperature and the 21-cm power spectrum, but they only have a limited effect on the neutral hydrogen fraction. We investigate how the observables are affected by changes in the underlying star formation model and by contribution from popIII stars. Finally, we forecast the capability of next-generation Hydrogen Epoch of Reionization Array (HERA) to detect the existence of FFB galaxies via power spectrum measurements. Our results show the possibility of a significant detection, provided that popII stars are the main drivers of lowering the spin temperature. Efficient popIII star formation will make the detection more challenging.