Sterile neutrino dark matter in $B-L$ extension of the standard model and galactic 511 keV line

TL;DR

This paper explores sterile right-handed neutrinos within a $U(1)_{B-L}$ extended standard model as a viable dark matter candidate that explains both relic density and galactic 511 keV photon flux.

Contribution

It demonstrates that MeV-scale sterile neutrinos in a low reheating scenario can simultaneously account for dark matter and the galactic 511 keV line.

Findings

Sterile neutrinos can be dark matter candidates in $U(1)_{B-L}$ models.

MeV-scale neutrinos explain the 511 keV photon flux.

Low reheating scenarios are compatible with observed relic density.

Abstract

Sterile right-handed neutrinos can be naturally embedded in a low scale gauged $U(1)_{B-L}$ extension of the standard model. We show that, within a low reheating scenario, such a neutrino is an interesting candidate for dark matter. We emphasize that if the neutrino mass is of order of MeV, then it accounts for the measured dark matter relic density and also accommodates the observed flux of 511 keV photons from the galactic bulge.