Detecting light axions from supernovae in nearby galaxies

TL;DR

This paper proposes a method to detect axion-like particles from supernovae in nearby galaxies through gamma-ray signals, potentially exploring new parameter space for ALP properties with decade-long gamma-ray and gravitational-wave observations.

Contribution

It introduces a novel extragalactic detection strategy for ALPs from supernovae, combining gamma-ray and gravitational-wave data to improve sensitivity to ALP-photon couplings.

Findings

Decade-long gamma-ray monitoring could reach sensitivities to ALP-photon coupling of g_{aγ} ≳ 10^{-16} GeV^{-1}.

The method can probe ALP masses m_a ≲ 10^{-9} eV.

Sensitivity surpasses the bounds set by SN 1987A observations.

Abstract

Axion-like particles (ALPs) coupled to nucleons can be efficiently produced in core-collapse supernovae (SNe) and then, if they couple to photons, convert into gamma rays in cosmic magnetic fields, generating short gamma-ray bursts. Though ALPs from a Galactic SN would induce an intense and easily detectable gamma-ray signal, such events are exceedingly rare. In contrast, a few SNe per year are expected in nearby galaxies within $\mathcal{O}(10)$ Mpc, where strong magnetic fields can enable more efficient ALP-photon conversions than in the Milky Way, offering a promising extragalactic target. This circumstance motivates full-sky gamma-ray monitoring, ideally combined with deci-hertz gravitational-wave detectors to enable time-triggered searches from nearby galaxies. We show that, under realistic conditions, a decade of coverage could reach sensitivities to ALP-photon coupling $g_{a \gamma} \gtrsim 10^{-16} \rm{GeV}^{-1}$ for ALP masses $m_a \lesssim 10^{-9} $ eV and assuming an ALP-nucleon coupling close to SN 1987A cooling bound. This sensitivity would allow one to probe a large, currently-unexplored region of the parameter space below the longstanding SN 1987A bound.