ON THE PSEUDO PHASE-SPACE DENSITY OF DARK MATTER HALOES AND THE UNIVERSALITY OF DENSITY PROFILES

We examine the radial dependence of the pseudo phase-space density, rho(r)/sigma(3)(r), for structures on galactic and galaxy cluster scales. We find that it is approximately a power-law only in the range of halo radius resolved by current simulations (down to 0.1% of the virial radius) while it has a non-power law behavior below the quoted scale, with inner profiles changing with mass. The non-power-law behavior is more evident for halos constituted of both dark matter and baryons, while halos constituted just of dark matter are characterized by an approximately power-law behavior. The results argue against universality of the pseudo phase-space density and, as a consequence, argue against universality of density profiles constituted of dark matter and baryons as also discussed in Del Popolo (2009).