The inner structure of dwarf sized halos in Warm and Cold Dark Matter
  cosmologies
  By means of N-body+Hydrodynamic zoom-in simulations we study the evolution of
the inner dark matter and stellar mass distributions of central dwarf galaxies
formed in halos of virial masses Mv=2-3x10^10 Msun at z=0, both in a WDM and
CDM cosmology. The half-mode mass in the WDM power spectrum of our simulations
is Mf= 2x 10^10 Msun. In the dark matter only simulations halo density profiles
are well described by the NFW parametric fit in both cosmologies, though the
WDM halos have concentrations lower by factors 1.5--2.0 than their CDM
counterparts. In the hydrodynamic simulations, the effects of baryons
significantly flatten the inner density, velocity dispersion, and pseudo
phase-space density profiles of the WDM halos but not of the CDM ones. The
density slope measured at ~ 0.02xRv, alpha, becomes shallow in periods of 2 to
5 Gyr in the WDM runs. We explore whether this flattening process correlates
with the global SF, Ms/Mv ratio, gas outflow, and internal specific angular
momentum histories. We do not find any clear trends but when alpha is shallower
than -0.5, Ms/Mv is always between 0.25 and 1%. We conclude that the main
reason of the formation of the shallow core is the presence of strong gas mass
fluctuations inside the inner halo, which are a consequence of the feedback
driven by a very bursty and sustained SF history in shallow gravitational
potentials. Our WDM halos, which assemble late and are less concentrated than
the CDM ones, obey these conditions. There are also (rare) CDM systems with
extended mass assembly histories that obey these conditions and form indeed
shallow cores. The dynamical heating and expansion processes, behind the DM
core flattening, apply also to the stars in a such a way that the stellar age
and metallicity gradients of the dwarfs are softened, their stellar half-mass
radii strongly grow with time, and their central surface densities decrease.
