Enhanced global signal of neutral hydrogen due to excess radiation at cosmic dawn

TL;DR

This paper demonstrates that including an early radio background significantly amplifies the 21cm absorption signal during cosmic dawn, improving prospects for future detection and emphasizing the need to consider excess radio backgrounds in models.

Contribution

It introduces a revised calculation of the global 21cm signal that accounts for an early radio background, highlighting its impact on the absorption feature during cosmic dawn.

Findings

Enhanced 21cm absorption signal with excess radio background

Potential for improved detection of cosmic dawn signals

Recommends including early radio backgrounds in future models

Abstract

We revisit the global 21cm signal calculation incorporating a possible radio background at early times, and find that the global 21cm signal shows a much stronger absorption feature, which could enhance detection prospects for future 21 cm experiments. In light of recent reports of a possible low-frequency excess radio background, we propose that detailed 21 cm calculations should include a possible early radio background.