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Session 82 - Gravitational Lensing & Dark Matter.
Oral session, Wednesday, January 15
Frontenac Ballroom,

[82.02] The Dynamical State of Clusters

G. K. Squires (Center for Particle Astrophysics)

Weak gravitational lensing provides a model independent method for determining the mass distribution on a variety of scales. Coupled with mass estimates from other methods (applications of the virial theorem and/or analyzes of the cluster X-ray emission), this also yields insight into the dynamical state of individual clusters. I present new results from wide field imaging of several intermediate redshift clusters, determining the 2D mass distribution and total mass from the weak gravitational lensing of background galaxies. I present comparisons with X-ray and/or virial analyses and discuss the implications of the agreements/disagreements among the methods. I also discuss the results of a previous analysis of A2218 and highlight the discrepancy between the lensing/X-ray mass estimates. The S-Z effect has been observed in this cluster and, coupled with X-ray data, the value of H_0 inferred ranges from H_O = 24 to 55 km s^-1 Mpc^-1. I discuss the utility of the weak lensing mass map for quantifying the systematic uncertainties in the assumptions underlying the H_0 determinations.

Program listing for Wednesday