Constraining Dark Matter with Merging Galaxy Clusters

We propose to observe two extraordinary, highredshift galaxy clusters from theMassive Cluster Survey (MACS). These targets have been selected as two of thebest examples of major mergers in the MACS catalogue, with clear evidence forconsiderable offset between the hot Xray emitting gas and optically luminousstellar material. Subaru and Hubble Space Telescope optical data for thesesystems have been gathered by us and will be used to carry out gravitationallensing reconstructions of the total cluster masses. XMM Xray data will be usedto probe the mass distribution of hot, baryonic gas, and produce detailed mapsof its thermodynamic state. The combination of these two mass measurements willbe used to constrain the properties of dark matter in these objects. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]