088471

We propose XMM-Newton+HST observations of SPT-CLJ2228 5828 comma a high-redshift openParz=0.73closePar galaxy cluster merger. It exhibits two widely-separated openPar940 kpcclosePar centers in the galaxy distribution with counterparts identified in a weak lensing analysis. From an SPT-SZ map comma the cluster gas appears to be located in between the two peaks of the galaxy distribution and mass map comma suggesting a dissociative merger. If confirmed comma SPT-CLJ2228 5828 would be among the widest dissociated mergers known. The requested high-resolution X-ray observations will allow us to confirm the dissociated merger nature and to constrain the cluster X-ray temperature and luminosity to 10%. We request complementary HST observations to substantially improve the mass reconstruction using strong and weak gravitational lensing.