Constraints on Axion-Like Particles from Ultra-High-Energy Observations of 3HWC J1908+063 with HAWC

TL;DR

This study uses HAWC gamma-ray data to search for signs of axion-like particles through their potential effect on gamma-ray spectra, setting new constraints on ALP properties in the process.

Contribution

First to analyze ultra-high-energy gamma-ray data for photon-ALP conversion effects, establishing new exclusion limits on ALP mass and coupling parameters.

Findings

No evidence of photon-ALP conversions was observed.

Set new constraints on ALP parameter space in the mass range $10^{-8}$ to $10^{-6}$ eV.

Derived exclusion limits for photon-ALP couplings between $10^{-12}$ and $10^{-10}$ GeV$^{-1}$.

Abstract

Axion-like particles (ALPs) are hypothetical particles and compelling candidates for cold dark matter. Their existence could be probed through their conversions into photons in the presence of magnetic fields. In this work, we explore the effect of these photon-ALP conversions by searching for an attenuation in the observed gamma ray spectra of galactic sources that emit at energies of hundreds of TeV. We analyze data from the High-Altitude Water Cherenkov (HAWC) Observatory for the source 3HWC J1908+063. No evidence of photon-ALP conversions was found, and we set constraints on the ALP parameter space. Specifically, we derive exclusion limits for ALPs with masses in the range $10^{-8}~\mathrm{eV} \leq m_a \leq 10^{-6}~\mathrm{eV}$ and photon-ALP couplings in the range $10^{-12}~\mathrm{GeV}^{-1} \leq g_{a\gamma} \leq 10^{-10}~\mathrm{GeV}^{-1}$, based on HAWC observations.