Evidences for Collisional Dark Matter In Galaxies?

The more we go deep into the knowledge of the dark component which embeds the stellar component of galaxies, the more we realize the profound interconnection between them. We show that the scaling laws among the structural properties of the dark and luminous matter in galaxies are too complex to derive from two inert components that just share the same gravitational field. In this paper we review the 30 years old paradigm of collisionless dark matter in galaxies. We found that their dynamical properties show strong indications that the dark and luminous components have interacted in a more direct way over a Hubble Time. The proofs for this are the presence of central cored regions with constant DM density in which their size is related with the disk lenghtscales. Moreover we find that the quantity $\rho_{DM}(r,L,R_D) \rho_\star (r,L,R_D)$ shows, in all objects, peculiarities very hardly explained in a collisionless DM scenario.