Contribution to the 2022 Cosmology session of the 56th Rencontres de Moriond: Reionization constraints from HERA 21cm power spectrum limits

TL;DR

This paper analyzes HERA 21cm power spectrum limits to constrain early universe reionization, the intergalactic medium, galaxy properties, and potential radio backgrounds, providing new bounds on these models.

Contribution

It introduces constraints on reionization and IGM properties using recent HERA 21cm data, especially focusing on possible radio backgrounds beyond the CMB.

Findings

Limits on radio background models are established.

Constraints on IGM ionization states are derived.

Comparison with existing radio and X-ray background constraints.

Abstract

I present our analysis of the 21cm power spectrum upper limits from the HERA radio interferometer, published in HERA Collaboration et al. 2022. We use the recent limits to constrain reionization and the properties of the IGM and galaxies in the early universe. I focus in particular on the possibility of a radio background in addition to the CMB (e.g. produced by early galaxies) which can lead to a stronger 21cm signal and is thus easier to constrain. I show what limits the HERA observations can put on these models and the IGM, and how this compares to existing constraints on the radio and X-ray background.