While numerical simulations universally produce a cuspy density profile, observed rotation curves of dwarf spiral and low surface brightness (LSB) galaxies, and the inner density profile of some clusters of galaxies give strong indication that the shape of the density profile at small scales is significantly shallower than profiles found in numerical simulations. The quoted discrepancy between simulations and observations has been often signaled as a genuine crisis of the LCDM scenario and has become known as the “cusp/ core� problem. In this talk, I review the problem and discuss some solutions. In particular, I discuss how a secondary infall model, taking into account the effect of ordered and random angular momentum, dynamical friction, and baryons adiabatic contraction, can produce profiles in agreement with observations.

Download the video:
09-26-2012_The_cusp_core_problem.avi (68min, 226MB)