DeepXMM‐NewtonandChandraObservations of Cl J1226.9+3332: A Detailed X‐Ray Mass Analysis of az= 0.89 Galaxy Cluster

Deep XMM and Chandra observations of ClJ1226.9+3332 at z=0.89 have enabledthe most detailed X-ray mass analysis of any such high-redshift galaxy cluster.The XMM temperature profile of the system shows no sign of central cooling,with a hot core and a radially declining profile. A temperature map showsasymmetry with a hot region that appears to be associated with a subclump ofgalaxies at the cluster redshift, but is not visible in the X-ray surfacebrightness. This is likely to be result of a merger event in the cluster, butdoes not appear to significantly affect the overall temperature profile. TheXMM temperature profile, and combined Chandra and XMM emissivity profileallowed precise measurements of the global properties of ClJ1226.9+3332; wefind kT=10.4+/-0.6keV, Z=0.16+/-0.05\Zsol, and M=5.2^{+1.0}_{-0.8}x10^{14}Msol.We obtain profiles of the metallicity, entropy, cooling time and gas fraction,and find a high concentration parameter for the total density profile of thesystem. The global properties are compared with the local LT and MT relations,and we are able to make the first observational test of the predicted evolutionof the YM relation. We find that departures from these scaling relations aremost likely caused by an underestimate of the total mass by ~30% in the X-rayhydrostatic mass analysis due to the apparent recent or ongoing mergeractivity.Comment: 14 pages, 19 figures. To be submitted to Ap