Properties of Resonantly Produced Sterile Neutrino Dark Matter Subhalos
  The anomalous 3.55 keV X-ray line recently detected towards a number of
massive dark matter objects may be interpreted as the radiative decays of 7.1
keV mass sterile neutrino dark matter. Depending on its parameters, the sterile
neutrino can range from cold to warm dark matter with small-scale suppression
that differs in form from commonly-adopted thermal warm dark matter. Here, we
numerically investigate the subhalo properties for 7.1 keV sterile neutrino
dark matter produced via the resonant Shi-Fuller mechanism. Using accurate
matter power spectra, we run cosmological zoom-in simulations of a Milky
Way-sized halo and explore the abundance of massive subhalos, their radial
distributions, and their internal structure. We also simulate the halo with
thermal 2.0 keV warm dark matter for comparison and discuss quantitative
differences. We find that the resonantly produced sterile neutrino model for
the 3.55 keV line provides a good description of structures in the Local Group,
including the number of satellite dwarf galaxies and their radial distribution,
and largely mitigates the too-big-to-fail problem. Future searches for
satellite galaxies by deep surveys, such as the Dark Energy Survey, Large
Synoptic Survey Telescope, and Wide Field Infrared Survey Telescope, will be a
strong direct test of warm dark matter scenarios.
