An XMM-Newton+HST study of an extreme comma high-redshift cluster merger

We propose XMMNewton+HST observations of SPTCLJ2228 5828, a highredshift(z0.73) galaxy cluster merger. It exhibits two widelyseparated (940 kpc)centers in the galaxy distribution with counterparts identified in a weaklensing analysis. From an SPTSZ map, the cluster gas appears to be located inbetween the two peaks of the galaxy distribution and mass map, suggesting adissociative merger. If confirmed, SPTCLJ2228 5828 would be among the widestdissociated mergers known. The requested highresolution Xray observations willallow us to confirm the dissociated merger nature and to constrain the clusterXray temperature and luminosity to 10%. We request complementary HSTobservations to substantially improve the mass reconstruction using strong and weak gravitational lensing. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]