Sterile neutrino dark matter bounds from galaxies of the Local Group

We show that the canonical oscillation-based (nonresonant) production of sterile neutrino dark matter is inconsistent at >99% confidence with observations of galaxies in the Local Group. We set lower limits on the nonresonant sterile neutrino mass of 2. 5 keV (equivalent to 0. 7 keV thermal mass) using phase-space densities derived for dwarf satellite galaxies of the Milky Way as well as limits of 8. 8 keV (equivalent to 1. 8 keV thermal mass) based on subhalo counts of N-body simulations of M 31 analogs. Combined with improved upper mass limits derived from significantly deeper x-ray data of M 31 with full consideration for background variations, we show that there remains little room for nonresonant production if sterile neutrinos are to explain 100% of the dark matter abundance. Resonant and nonoscillation sterile neutrino production remain viable mechanisms for generating sufficient dark matter sterile neutrinos.