AAS 203rd Meeting, January 2004
Session 30 Galaxy Clusters and Large Scale Structure I
Oral, Monday, January 5, 2004, 2:00-3:30pm, Centennial I/II

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[30.04] The Total Density Profile in Galaxy Clusters Inferred From a Systematic Search for Radial Arcs in the HST/WFPC2 Archive

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

The Cold Dark Matter (CDM) picture of structure formation predicts that the density profile of DM halos are universal in form across a wide range of mass scales from dwarf galaxies to clusters of galaxies. A useful probe to test this prediction at the galaxy cluster scale are radial gravitational arcs, which are sensitive to the derivative of the mass enclosed. We have undertaken the first systematic search for radial gravitational arcs using the entire WFPC2 archive. This search has yielded well over a dozen radial arc systems and has also uncovered many other possible lensing features. Previously we have performed a lensing + dynamical analysis in three radial arc clusters for which we have found the DM profile to be significantly shallower than that predicted from CDM simulations. Here we will discuss the heterogeneous HST/WFPC2 sample and the radial arc search strategy. By taking appropriate subsamples of the data, we have measured the mean total density profile in the central regions of galaxy clusters. In this radial regime we are sensitive to the controversial "inner slope" of the DM density profile, allowing us to test the predictions of numerical simulations of CDM halos. We acknowledge financial support from proposal number HST-AR-09527 provided by NASA through STScI.

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

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.