Supernova bounds on axion-like particles coupled with nucleons and electrons

Understand

We investigate the potential of type II supernovae (SNe) to constrain axion-like particles (ALPs) coupled simultaneously to nucleons and electrons.

• ALPs coupled to nucleons can be efficiently produced in the SN core via nucleon-nucleon bremsstrahlung and, for a wide range of parameters, leave the SN unhindered, producing a large ALP flux.
• For masses exceeding 1 MeV, these ALPs would decay into electron-positron pairs, generating a positron flux.
• In the case of Galactic SNe, the annihilation of the created positrons with the electrons present in the Galaxy would contribute to the 511 keV annihilation line.