511 keV line constraints on feebly interacting particles from supernovae

Understand

Feebly interacting particles with masses with O(10-100) MeV can be copiously produced by core-collapse supernovae (SNe).

• In this paper we consider the case of MeV-ish sterile neutrinos and dark photons mixed with ordinary neutrinos and photons, respectively.
• Furthermore, both sterile neutrinos and dark photons may decay into positrons on their route to Earth.
• Such positrons would annihilate with electrons in the Galactic medium and contribute to the photon flux in the 511 keV line.