XMM-Newton Observations of the ACT Cosmological Sample of Clusters

We propose to complete our Xray followup program aimed at observing the ACTCosmological Sample of Clusters, which is a welldefined sample of 22 massivegalaxy clusters detected by the Atacama Cosmology Telescope using theSunyaevZel.dovich effect (SZE). There remain five newlydiscovered SZE clustersin this sample without any Xray data. The proposed XMMNewton EPIC observationswill provide accurate gas masses and temperatures to be used for a precisioncalibration of the SZE signal versus mass scaling law out to redshifts of 1.This effort is an essential part of our intensive multiwavelength campaign toobtain mass measurements for the ACT Cosmological Sample of Clusters. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]