Closing in on Resonantly Produced Sterile Neutrino Dark Matter
  We perform an exhaustive scan of the allowed resonant production regime for
sterile neutrino dark matter in order to improve constraints for dark matter
structures which arise from the non-thermal sterile neutrino energy spectra.
Small-scale structure constraints are particularly sensitive to large lepton
asymmetries/small mixing angles which result in relatively warmer sterile
neutrino momentum distributions. We revisit Milky Way galaxy subhalo count
constraints and combine them with recent searches for X-ray emission from
sterile neutrino decays. Together they rule out models outside the mass range
7.0 keV < m_nu_s < 36 keV and lepton asymmetries smaller than 15 x 10-6 per
unit entropy density at 95 percent CI or greater. We also find that while a
portion of the parameter space remains unconstrained, the combination of
subhalo counts and X-ray data indicate the candidate 3.55 keV X-ray line signal
potentially originating from a 7.1 keV sterile neutrino decay to be disfavored
at 93 percent CI.
