The ESO Nearby Abell Cluster Survey. XII. The Mass and Mass‐to‐Light Ratio Profiles of Rich Clusters

We determine the mass profile of an ensemble cluster built from 3056 galaxies in 59 nearby clusters observed in the ESO Nearby Abell Cluster Survey. The mass profile is derived from the distribution and kinematics of the Early-type (elliptical and S0) galaxies only, with projected distances from the centers of their clusters ≤ 1.5r200. These galaxies are most likely to meet the conditions for the application of the Jeans equation, since they are the oldest cluster population, and are thus quite likely to be in dynamical equilibrium with the cluster potential. In addition, the assumption that the Early-type galaxies have isotropic orbits is supported by the shape of their velocity distribution. For galaxies of other types (the brightest ellipticals with MR ≤ −22+5log h, and the early and late spirals) these assumptions are much less likely to be satisfied. For the determination of the mass profile we also exclude Early-type galaxies in subclusters. Application of the Jeans equation yields a non-parametric estimate of the cumulative mass profile M(< r), which has a logarithmic slope of −2.4 ± 0.4 in the density profile at r200 (approximately the virial radius). We compare our result with