Blazar Constraints on Axions through New Spectral Modulation Searches in 1ES 1959+650 & B2 1811+31

TL;DR

This study searches for axion-induced spectral modulations in blazar gamma-ray data, setting new constraints on axion-photon coupling, and highlights the importance of modeling uncertainties in such astrophysical searches.

Contribution

It introduces a novel method of searching for axions via spectral modulations in blazar gamma-ray spectra and assesses the impact of modeling uncertainties on the constraints.

Findings

No evidence for axions in the analyzed blazars.

Set exclusion limits on axion-photon coupling for specific mass ranges.

Demonstrated the significance of modeling uncertainties in spectral analyses.

Abstract

Blazars are unique astrophysical environments whose high-energy $\gamma$-ray spectra are susceptible to modulations in the presence of ultralight axions. We search for these modulations, induced by axion-photon mixing, in Fermi-LAT spectral data of previously unexplored blazar targets, focusing in particular on blazars 1ES 1959+650 and B2 1811+31, whose flare states provide a clean testbed for axion activity. In both cases, we find no evidence for axions, and set exclusion regions on the axion-photon coupling for masses between $10^{-9}$ eV $\lesssim$ $m_a$ $\lesssim$ $10^{-8}$ eV, with sensitivities typically reaching $g_{a \gamma \gamma} \sim 10^{-11} - 10^{-10}$ GeV$^{-1}$ depending on the assumed blazar modeling choices. We examine the broad impact of modeling uncertainties, finding that the resulting constraints can vary substantially across plausible configurations. We discuss the implications of these systematic effects and their relevance for similar blazar-like searches in the future.