Probing Heavy Axion-like Particles from Massive Stars with X-rays and Gamma Rays

TL;DR

This paper explores the potential to detect heavy axion-like particles produced in massive stars through their decay into photons, using X-ray and gamma-ray telescopes, thereby probing new regions of ALP parameter space.

Contribution

It demonstrates that stellar environments can produce detectable heavy ALPs and estimates the sensitivity of current and future telescopes to these particles.

Findings

Current telescopes can probe axion-photon couplings down to ~4×10^{-11} GeV^{-1}.

Heavy ALPs with masses 10-100 keV can be detected via their decay into photons.

The study extends the search for ALPs into a new mass and coupling parameter space.

Abstract

The hot interiors of massive stars in the later stages of their evolution provide an ideal place for the production of heavy axion-like particles (ALPs) with mass up to O(100 keV) range. We show that a fraction of these ALPs could stream out of the stellar photosphere and subsequently decay into two photons that can be potentially detected on or near the Earth. In particular, we estimate the photon flux originating from the spontaneous decay of heavy ALPs produced inside Horizontal Branch and Wolf-Rayet stars, and assess its detectability by current and future $X$-ray and gamma-ray telescopes. Our results indicate that current and future telescopes can probe axion-photon couplings down to $g_{a\gamma} \sim 4\times 10^{-11}$ GeV${}^{-1}$ for $m_a\sim 10-100$ keV, which covers new ground in the ALP parameter space.