The Cusp/Core problem and the Secondary Infall Model
  We study the cusp/core problem using a secondary infall model (SIM) that
takes into account the effect of ordered and random angular momentum, dynamical
friction and baryons adiabatic contraction. The model is applied to structures
on galactic scales (normal and dwarfs spiral galaxies) and on clusters of
galaxies scales. Our analysis suggest that angular momentum and dynamical
friction are able, on galactic scales, to overcome the competing effect of
adiabatic contraction eliminating the cusp. The slope of density profile of
inner haloes flattens with decreasing halo mass and the profile is well
approximated by a Burkert's profile. In order to obtain the NFW profile,
starting from the profiles obtained from our model, the magnitude of angular
momentum and dynamical friction must be reduced with respect to the values
predicted by the model itself. The rotation curves of four LSB galaxies from
Gentile et al. (2004) are compared to the rotation curves obtained by the model
in the present paper obtaining a good fit to the observational data. The time
evolution of the density profile of a galaxy of $10^8-10^9 M_{\odot}$ shows
that after a transient steepening, due to the adiabatic contraction, the
density profile flattens to $\alpha \simeq 0$. On cluster scales we observe a
similar evolution of the dark matter density profile but in this case the
density profile slope flattens to $\alpha \simeq 0.6$ for a cluster of $\simeq
10^{14} M_{\odot}$. The total mass profile, differently from that of dark
matter, shows a central cusp well fitted by a NFW model.
