We show that the canonical oscillation-based ( non-resonant ) 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 non-resonant 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 analogues .
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 non-resonant production if sterile neutrinos are to explain 100 % of the dark matter abundance .
Resonant and non-oscillation sterile neutrino production remain viable mechanisms for generating sufficient dark matter sterile neutrinos .