The radial profiles of the different mass components in galaxy clusters

Abstract

Aims. To derive the mass profiles of the different luminous and dark components in clusters. Methods. The cluster mass profile is determined by using the Jeans equation applied to the projected phase-space distribution of about 3000 galaxies members of 59 nearby clusters from the ESO Nearby Abell Cluster Survey. The baryonic and subhaloes mass components are determined from the galaxies' luminosity-density profiles through scaling relations between luminosities and baryonic and dark halo masses. The baryonic mass component associated with the intra-cluster gas is determined using X-ray data from ROSAT. Results. The baryon-to-total mass fraction decreases from a value of ≃0. 12 near the center to ≃0.08 at the distance of ≃0.15 virial radii, then it increases again, to reach a value of ≃0.14 at the virial radius. Diffuse, cluster-scale dark matter dominates at all radii, but its contribution to the total mass content decreases outwards to the virial radius, where the dark matter in subhaloes may contribute up to ≃23%, and the baryons ≃14% of the total mass. The dark mass and diffuse dark mass profiles are well fit by both cuspy and cored models. The subhalo mass distribution is not fit by either model. © ESO 2005.