Axion-like Particles Implications for High-Energy Astrophysics

Abstract

We offer a pedagogical introduction to axion-like particles (ALPs) as far as their relevance for high-energy astrophysics is concerned, from a few MeV to 1000 TeV. This review is self-contained, in such a way to be understandable even to non-specialists. Among other things, we discuss two strong hints at a specific ALP that emerge from two very different astrophysical situations. More technical matters are contained in three Appendices.

Keywords

• particle physics
• astroparticle physics
• axion-like particles
• photon polarization
• blazars
• galaxy clusters