Photon enhancement in a homogeneous axion dark matter background

TL;DR

This paper investigates how a homogeneous axion dark matter background can stimulate photon production through parametric instability, potentially impacting astrophysical structures like miniclusters and galactic halos.

Contribution

It provides an analytical estimate of photon enhancement due to axion decay stimulation in both coherent and non-coherent fields, highlighting its astrophysical relevance.

Findings

Photon field exhibits parametric instability near half the axion mass.

Analytical estimates of photon enhancement in different axion field coherence states.

Potential significance for astrophysical objects such as miniclusters and galactic halos.

Abstract

We study the propagation of photons in a homogeneous axion dark matter background. When the axion decay into two photons is stimulated, the photon field exhibits a parametric instability in a small bandwidth centered on one half of the axion mass. We estimate analytically the enhancement for both coherent and non-coherent axion fields and we find that this effect could be relevant in the context of miniclusters and galactic halos.