Properties of subhalos in the interacting dark matter scenario
  One possible and natural derivation from the collisionless cold dark matter
(CDM) standard cosmological framework is the assumption of the existence of
interactions between dark matter (DM) and photons or neutrinos. Such possible
interacting dark matter (IDM) model would imply a suppression of small-scale
structures due to a large collisional damping effect, even though the weakly
interacting massive particle (WIMP) can still be the DM candidate. Because of
this, IDM models can help alleviate alleged tensions between standard CDM
predictions and observations at small mass scales. In this work, we investigate
the properties of DM halo substructure or subhalos formed in a high-resolution
cosmological N-body simulation specifically run within these alternative
models. We also run its CDM counterpart, which allowed us to compare subhalo
properties in both cosmologies. We show that, in the lower mass range covered
by our simulation runs, both subhalo concentrations and abundances are
systematically lower in IDM compared to the CDM scenario. Yet, as in CDM, we
find that median IDM subhalo concentration values increase towards the
innermost regions of their hosts for same mass subhalos. Also similarly to CDM,
we find IDM subhalos to be more concentrated than field halos of the same mass.
Our work has a direct application on studies aimed at the indirect detection of
DM where subhalos are expected to boost the DM signal of their host halos
significantly. From our results, we conclude that the role of halo substructure
in DM searches will be less important in interacting scenarios than in CDM, but
is nevertheless far from being negligible.
