Photon-axion conversion in Active Galactic Nuclei?

Understand

Axion-Like Particles (ALPs) are the focus of intense current research.

• We analyze photon-ALP conversion in the context of relativistic jet models of Active Galactic Nuclei (AGN) for more than 100 sources.
• Contrary to previous claims, we find that this process cannot occur above 100 GeV regardless of the actual AGN model and the values of ALP parameters.
• This result rules out a proposed strategy to bypass the cosmic opacity above 100 GeV, as apparently required by observations.