Sterile neutrino dark matter catalyzed by a very light dark photon

Abstract

Sterile neutrinos (νs) that mix with active neutrinos (νa) are interesting dark matter candidates with a rich cosmological and astrophysical phenomenology.In their simplest incarnation, their production is severely constrained by a combination of structure formation observations and X-ray searches.We show that if active neutrinos couple to an oscillating condensate of a very light L μ-L τ gauge field, resonant νa-νs oscillations can occur in the early universe, consistent with νsconstituting all of the dark matter, while respecting X-ray constraints onνs→νaγ decays. Interesting deviations from standard solar and atmospheric neutrino oscillations can persist to the present.