Irregularity in gamma ray source spectra as a signature of axionlike particles

TL;DR

This paper proposes a novel method to detect axionlike particles by identifying irregularities in gamma ray source spectra, challenging previous assumptions about their spectral signatures and offering a falsifiable signature.

Contribution

It introduces a new approach to search for photon-ALP oscillations by analyzing spectral irregularities in individual gamma ray sources, rather than relying on average spectral features.

Findings

Spectral irregularities can indicate photon-ALP oscillations.

The method distinguishes ALP signatures from astrophysical processes.

It provides a falsifiable signature for ALP detection.

Abstract

Oscillations from high energy photons into light pseudoscalar particles in an external magnetic field are expected to occur in some extensions of the standard model. It is usually assumed that those axionlike particles (ALPs) could produce a drop in the energy spectra of gamma ray sources and possibly decrease the opacity of the Universe for TeV gamma rays. We show here that these assumptions are in fact based on an average behavior that cannot happen in real observations of single sources. We propose a new method to search for photon-ALP oscillations, taking advantage of the fact that a single observation would deviate from the average expectation. Our method is based on the search for irregularities in the energy spectra of gamma ray sources. We predict features that are unlikely to be produced by known astrophysical processes and a new signature of ALPs that is easily falsifiable.