ON THE UNIVERSALITY OF DENSITY PROFILES

The secondary infall model (described in a previous paper by this author), which takes into account the effect of dynamical friction, ordered and random angular momentum, baryon adiabatic contraction and dark matter (DM) baryon interplay, is used to study how the inner slopes of relaxed CDM haloes with and without baryons (baryons+DM and pure DM) depend on redshift and on halo mass. This method is applied to structures on galactic scales and clusters of galaxies scales. It is found that the inner logarithmic density slope, α ≡ d log ρ/d log r, of DM haloes with baryons has a significant dependence on halo mass and redshift, with slopes ranging from α 0 for dwarf galaxies to α 0.4 for objects of M 1013M and α 0.94 forM 1015M clusters of galaxies. Structure slopes increase with increasing redshift, and this trend reduces going from galaxies to clusters. In the case of density profiles constituted just of DM, the mass and redshift dependence of the slope are very slight. In this last case, the analysis of Merritt et al. is used. They compared N-body density profiles with various parametric models, finding systematic variation in the profile shape with halo mass. This last analysis suggests that the galaxy-sized haloes obtained with this model have a different shape parameter (i.e. a different mass distribution) than the clustersized haloes obtained with the same model. The results of the present paper argue against universality of density profiles constituted by DM and baryons and confirm the claims of a systematic variation in profile shape with halo mass, for DM haloes.