AAS 205th Meeting, 9-13 January 2005
Session 157 Cluster of Galaxies and Dark Matter
Oral, Thursday, January 13, 2005, 10:00-11:30am, Pacific 2/3

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[157.05] The Dark Matter Density Profile of Galaxy Clusters

D.J. Sand, T. Treu, R.S. Ellis, G.P. Smith (Caltech)

One of the basic predictions of the Cold Dark Matter picture of structure formation is that the density profiles of DM halos are 'cuspy' in form across a wide range of mass scales from dwarf galaxies to clusters of galaxies. Here we describe two projects which seek to constrain the slope of the dark matter density profile in galaxy clusters. First, we undertook a survey which simultaneously modeled strong lensing constraints and the velocity dispersion profile of the brightest cluster galaxy in order to separate dark and luminous mass components and probe the DM directly. Doing this, we found that DM profiles are in general shallower than predicted from CDM simulations. Second, a search of the HST/WFPC2 archive was initiated to find new arc systems and to ascertain their properties. A total of 129 clusters yielded 104 tangential and 12 radial arcs. Modeling the expected number ratio of radial to tangential arcs, we constrained the slope of the inner DM density profile. By including a secondary mass component, representing the brightest cluster galaxy, the constraints are weakened and consistent with a range of inner DM slopes.

The author(s) of this abstract have provided an email address for comments about the abstract: djs@astro.caltech.edu

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© 2004. The American Astronomical Society.