Complete history of the observable 21-cm signal from the first stars during the pre-reionization era

TL;DR

This paper provides the first comprehensive calculation of the 21-cm signal's evolution during the era of the first stars, incorporating large-scale fluctuations and feedback effects, with predictions for detectability by SKA.

Contribution

It introduces a hybrid computational approach to model the inhomogeneous 21-cm signal from the first stars, accounting for complex feedback mechanisms and large-scale structure.

Findings

Fluctuations in the 21-cm signal are driven by density and radiative backgrounds.

Ly-alpha fluctuations at z ~ 25 are potentially detectable with SKA.

Star formation is suppressed by Lyman-Werner feedback and relative velocities.

Abstract

We present the first complete calculation of the history of the inhomogeneous 21-cm signal from neutral hydrogen during the era of the first stars. We use hybrid computational methods to capture the large-scale distribution of the first stars, whose radiation couples to the neutral hydrogen emission, and to evaluate the 21-cm signal from z ~ 15-35. In our realistic picture large-scale fluctuations in the 21-cm signal are sourced by the inhomogeneous density field and by the Ly-alpha and X-ray radiative backgrounds. The star formation is suppressed by two spatially varying effects: negative feedback provided by the Lyman-Werner radiative background, and supersonic relative velocities between the gas and dark matter. Our conclusions are quite promising: we find that the fluctuations imprinted by the inhomogeneous Ly-alpha background in the 21-cm signal at z ~ 25 should be detectable with the Square Kilometer Array.