Constraints on Axion-photon coupling from the Global 21-cm Signal

TL;DR

This paper investigates how axion-photon interactions could influence the global 21-cm signal, constraining the parameters of axion models based on observational data.

Contribution

It provides new constraints on axion-photon coupling parameters by analyzing their effects on the global 21-cm signal and related astrophysical phenomena.

Findings

Viable parameter space regions satisfy observational and physical constraints.

Axion-photon coupling can generate primordial magnetic fields post-recombination.

Certain axion parameters are compatible with 21-cm observations and black hole formation requirements.

Abstract

A radiation field can be excited via parametric resonance when an oscillating axion field couples to the electromagnetic sector through a Chern-Simons interaction. As demonstrated in previous works, this mechanism can generate primordial magnetic fields shortly after recombination and provide sufficient ultraviolet radiation for the formation of direct collapse black holes (DCBHs). In this study, I analyze constraints on the parametric resonance scenario from global 21cm observations. I find that there exist viable regions in the parameter space that satisfy both observational limits and the physical requirements of the magnetic field and DCBH formation scenarios.