Structure formation in Multiple Dark Matter cosmologies with long-range
  scalar interactions
  (Abridged) An interaction between Cold Dark Matter (CDM) and a classical
scalar field playing the role of the cosmic dark energy (DE) might provide
long-range dark interactions without conflicting with solar system bounds.
Although presently available observations allow to constrain such interactions
to a few percent of the gravitational strength, some recent studies have shown
that if CDM is composed by two different particle species having opposite
couplings to the DE field, such tight constraints can be considerably relaxed,
allowing for long-range scalar forces of order gravity without significantly
affecting observations both at the background and at the linear perturbations
level. In the present work, we extend the investigation of such Multiple Dark
Matter scenarios to the nonlinear regime of structure formation, by presenting
the first N-body simulations ever performed for these cosmologies. Our results
highlight some characteristic footprints of long-range scalar forces that arise
only in the nonlinear regime for specific models that would be otherwise
practically indistinguishable from the standard LCDM scenario both in the
background and in the growth of linear density perturbations. Among these
effects, the formation of "mirror" cosmic structures in the two CDM species,
the suppression of the nonlinear matter power spectrum at k > 1 h/Mpc, and the
fragmentation of collapsed halos, represent peculiar features that might
provide a direct way to constrain this class of cosmological models.
