The Burst Cluster: Dark Matter in a Merging Cluster Host of the Short GRB050509B

We propose a 132 ksec XMMNewton observations of ZwCl 1234.0+02916 (z0.2214), amerging galaxy cluster where one of the BCGs hosted the short GRB 050509B. OurChandra observation shows a bimodal structure, with a possible cold front at thewestern edge, indicating that the two subclusters are moving away from oneanother after first core passage. Our weak lensing analysis shows that the darkmatter is also bimodal, and is centered on the two galaxy distributions, whilethe Xray gas lags behind (like the Bullet cluster). XMM data will confirm thebimodal structure and will allow the measurement of the merger velocity and thestudy of the segregation of dark and baryonic matter. This is likely to be ahigh velocity collision which will constrain dark matter. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]