paper

The ESO Nearby Abell Cluster Survey. XII. The mass and mass-to-light-ratio profiles of rich clusters

arXiv:astro-ph/0310060 · doi:10.1086/380118

Abstract

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, which are most likely to meet the conditions for the application of the Jeans equation. We assume that the Early-type galaxies have isotropic orbits, as supported by the shape of their velocity distribution. The brightest ellipticals (with M_R < -22+5 log h), and the Early-type galaxies in subclusters are excluded from the sample. 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 the virial radius. We compare our result with several analytical models from the literature (NFW, Moore et al. 1999, softened isothermal sphere, and Burkert 1995) and find that all are acceptable. However, our data do not provide compelling evidence for the existence of a core; as a matter of fact, the best-fitting core models have core-radii well below 100/h kpc. The upper limit we put on the size of the core-radius provides a constraint for the scattering cross-section of dark matter particles. The total-mass density appears to be traced remarkably well by the luminosity density of the Early-type galaxies. On the contrary, the luminosity density of the brightest ellipticals increases faster towards the center than the mass density, while the luminosity density profiles of the early and late spirals are somewhat flatter than the mass density profile. (Abridged)

arXiv commentApJ, accepted

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