Subhaloes in Self-Interacting Galactic Dark Matter Haloes
  We present N-body simulations of a new class of self-interacting dark matter
models, which do not violate any astrophysical constraints due to a
non-power-law velocity dependence of the transfer cross section which is
motivated by a Yukawa-like new gauge boson interaction. Specifically, we focus
on the formation of a Milky Way-like dark matter halo taken from the Aquarius
project and re-simulate it for a couple of representative cases in the allowed
parameter space of this new model. We find that for these cases, the main halo
only develops a small core (~1 kpc) followed by a density profile identical to
that of the standard cold dark matter scenario outside of that radius. Neither
the subhalo mass function nor the radial number density of subhaloes are
altered in these models but there is a significant change in the inner density
structure of subhaloes resulting in the formation of a large density core. As a
consequence, the inner circular velocity profiles of the most massive subhaloes
differ significantly from the cold dark matter predictions and we demonstrate
that they are compatible with the observational data of the brightest Milky Way
dSphs in such a velocity-dependent self-interacting dark matter scenario.
Specifically, and contrary to the cold dark matter case, there are no subhaloes
that are more concentrated than what is inferred from the kinematics of the
Milky Way dSphs. We conclude that these models offer an interesting alternative
to the cold dark matter model that can reduce the recently reported tension
between the brightest Milky Way satellites and the dense subhaloes found in
cold dark matter simulations.
