Properties of Local Group galaxies in hydrodynamical simulations of
  sterile neutrino dark matter cosmologies
  We study galaxy formation in sterile neutrino dark matter models that differ
signifi- cantly from both cold and from `warm thermal relic' models. We use the
EAGLE code to carry out hydrodynamic simulations of the evolution of pairs of
galaxies chosen to resemble the Local Group, as part of the APOSTLE simulations
project. We compare cold dark matter (CDM) with two sterile neutrino models
with 7 keV mass: one, the warmest among all models of this mass (LA120) and the
other, a relatively cold case (LA10). We show that the lower concentration of
sterile neutrino subhalos compared to their CDM counterparts makes the inferred
inner dark matter content of galaxies like Fornax (or Magellanic Clouds) less
of an outlier in the sterile neutrino cosmologies. In terms of the galaxy
number counts the LA10 simulations are indistinguishable from CDM when one
takes into account halo-to-halo (or `simulation-to-simulation') scatter. In
order for the LA120 model to match the number of Local Group dwarf galaxies, a
higher fraction of low mass haloes is required to form galaxies than is
predicted by the EAGLE simulations. As the census of the Local Group galaxies
nears completion, this population may provide a strong discriminant between
cold and warm dark matter models.
