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A. Mahdavi (Institute for Astronomy, University of Hawaii), M. J. Geller (Harvard-Smithsonian Center for Astrophysics)
We improve existing techniques for constraining the mass profile and orbital structure of nearby groups and clusters of galaxies. Our method yields the joint probability distribution of the inner density slope \lambda, the velocity anisotropy, and the core radius for these systems. We incorporate 2419 new redshifts in the fields of 41 groups of galaxies with z < 0.04, as well as 1181 archived redshifts in the fields of 10 dynamically relaxed clusters with z < 0.1. We combine groups and clusters that have statistically consistent velocity dispersion profiles (VDPs); these turn out to be systems with declining VDPs, even though we place no requirements on the VDP shapes when we test for consistency. Our analysis yields \lambda = 1.3-1.9 for groups and \lambda = 0-0.7 for clusters, suggesting that richer systems of galaxies have flatter dark matter density profiles.
The author(s) of this abstract have provided an email address for comments about the abstract: amahdavi@cfa.harvard.edu