Caustic and Weak Lensing Estimators of Galaxy Cluster Masses

Abstract

There are only two methods for estimating the mass distribution in the outer regions of galaxy clusters, where virial equilibrium does not hold: weak gravitational lensing and identification of caustics in redshift space. For the first time, we apply both methods to three clusters: A2390, MS1358 and Cl 0024. The two measures are in remarkably good agreement out to ~2 Mpc/h from the cluster centers. This result demonstrates that the caustic technique is a valuable complement to weak lensing. With a few tens of redshifts per (Mpc/h)^2 within the cluster, the caustic method is applicable for any z<~0.5.

5 pages, 1 figure, ApJ Letters, in press