Evidence for an axion-like particle from blazar spectra?

TL;DR

Recent gamma-ray observations suggest the universe is more transparent than expected, supporting the hypothesis that axion-like particles facilitate photon oscillations in cosmic magnetic fields.

Contribution

This paper provides evidence from recent observations that bolster the DARMA scenario, indicating the likely existence of axion-like particles affecting gamma-ray propagation.

Findings

Observations support the universe's increased transparency to gamma rays.

Data aligns with photon-axion oscillation models in cosmic magnetic fields.

Supports the existence of axion-like particles as a natural explanation.

Abstract

Observations with the Imaging Atmospheric Cherenkov Telescopes H.E.S.S., MAGIC, CANGAROO III and VERITAS have shown that the Universe is more transparent than expected to gamma rays above 100GeV. As a natural explanation, the DARMA scenario has previously been proposed, wherein photons can oscillate into a new very light axionlike particle and vice-versa in the presence of cosmic magnetic fields. Here we demonstrate that the most recent observations further support the DARMA scenario, thereby making the existence of a very light axion-like particle more likely.