Gamma Ray Signals from Cosmic Ray Scattering on Axion-Like Particles

TL;DR

This paper investigates gamma-ray signals produced by cosmic ray electrons scattering on axion-like particles, providing new constraints on ALP-electron couplings and discussing future detection prospects with improved gamma-ray observations.

Contribution

It introduces a novel method to constrain ALP-electron couplings using cosmic ray scattering-induced gamma-ray signals, extending current bounds and exploring future observational capabilities.

Findings

Current Fermi data constrains ALP-electron couplings.

Future e-Astrogram observations could improve sensitivity.

Bounds may be superseded by lifetime constraints in some models.

Abstract

Dark Matter (DM) may be comprised of axion-like particles (ALPs) with couplings to photons and the standard model fermions. In this paper we study photon signals arising from cosmic ray (CR) electron scattering on background ALPs. For a range of masses we find that these bounds can place competitive new constraints on the ALP-electron coupling, although in many models lifetime constraints may supersede these bounds. In addition to current Fermi constraints, we also consider future e-Astrogram bounds which will have greater sensitivity to ALP-CR induced gamma-rays.