Magnetic Turbulence Boosts Supernova Signals of Axion-Photon Conversion

TL;DR

This paper demonstrates that small-scale turbulent magnetic fields significantly enhance axion-photon conversion signals from supernovae, improving constraints on axion couplings by up to two orders of magnitude.

Contribution

It introduces the impact of turbulent magnetic fields on axion-photon conversion, extending sensitivity to larger axion masses and improving existing constraints.

Findings

Turbulent magnetic fields boost axion-photon conversion signals.

Sensitivity to axion couplings is improved by up to two orders of magnitude.

Turbulence likely affects other astrophysical axion searches.

Abstract

Magnetic fields between a supernova (SN) and Earth convert axions into gamma rays. The absence of such a signal in coincidence with SN 1987A neutrinos, using the coherent Milky Way field, provides well-studied constraints on $g_{ap}\times g_{a\gamma}$ (axion-proton times axion-photon couplings) and on $g_{a\gamma}$ alone. We show that the small-scale power of the turbulent magnetic field component boosts axion-photon conversion and, crucially, extends sensitivity to larger masses. The turbulent field components of the Milky Way and of the Large Magellanic Cloud (hosting SN 1987A) yield improvements of up to two orders of magnitude in $g_{ap}\times g_{a\gamma}$. Turbulence should likely impact the sensitivity of other searches based on other axion-photon conversion sites, such as starburst galaxies.