Astrophysical Haloscopes

TL;DR

This paper explores the potential for detecting axion-like particle dark matter through radio signals generated by cosmic magnetic fields, highlighting the possibility of observing detectable signals from stellar winds and their implications for understanding magnetic field structures.

Contribution

It provides calculations of radio photon fluxes from axion-like particles in cosmic magnetic fields and discusses the feasibility of detection and its implications for magnetic field studies.

Findings

Detectable radio signals may originate from stellar winds with strong magnetic fields.

Flux predictions are highly uncertain due to unknown magnetic field structures.

Potential for combined astrophysical and laboratory detection to inform magnetic field properties.

Abstract

We compute the fluxes of radio photons from conversion of axion-like particle dark matter in cosmic magnetic fields. We find that for axion-like particle masses around $10^{-6}\,$eV and effective coupling constants to photons $g_{a\gamma}\gtrsim10^{-13}\,{\rm GeV}^{-1}$ strongly magnetized nearby stellar winds may give detectable line-like radio photon signals, although predicted fluxes are highly uncertain due to the poorly known structure of the magnetic fields. Nevertheless, it may be worth while to conduct a dedicated search in the direction of such sources. When combined with a possible future laboratory detection of axion-like dark matter such observations may in turn provide information on the small scale magnetic field structure in such objects.