A New Light Boson from Cherenkov Telescopes Observations?

TL;DR

This paper proposes that photon oscillations into axion-like particles in extragalactic magnetic fields can explain the unexpectedly high transparency of the universe to very-high-energy gamma rays, aligning observations with standard blazar models.

Contribution

It introduces a novel explanation involving axion-like particles for gamma-ray transparency, supported by quantitative estimates matching observed spectra.

Findings

Photon oscillations can account for the observed transparency.

Predictions are testable with current gamma-ray detectors.

Standard blazar models are compatible with these effects.

Abstract

Early indications by H.E.S.S. and the subsequent detection of blazar 3C279 by MAGIC show that the Universe is more transparent to very-high-energy gamma rays than previously thought. We demonstrate that this circumstance can be reconciled with standard blazar emission models provided that photon oscillations into a very light Axion-Like Particle occur in extragalactic magnetic fields. A quantitative estimate of this effect indeed explains the observed spectrum of 3C279. Our prediction can be tested by the satellite-borne Fermi/LAT detector as well as by the ground-based Imaging Atmospheric Cherenkov Telescopes H.E.S.S., MAGIC, CANGAROO III, VERITAS and by the Extensive Air Shower arrays ARGO-YBJ and MILAGRO.