Deep Xmm-newton and Chandra Observations of Clj1226.9+3332: a Detailed X-ray Mass Analysis of a Z = 0.89 Galaxy Cluster

Deep XMM-Newton and Chandra observations of ClJ1226.9+3332 at z = 0.89 have enabled the most detailed X-ray mass analysis of any such high-redshift galaxy cluster. The XMM-Newton temperature profile of the system shows no sign of central cooling, with a hot core and a radially declining profile. A temperature map shows asymmetry with a hot region that appears to be associated with a subclump of galaxies at the cluster redshift, but is not visible in the X-ray surface brightness. This is likely to be result of a merger event in the cluster, but does not appear to significantly affect the overall temperature profile. The XMM-Newton temperature profile, and combined Chandra and XMMNewton emissivity profile allowed precise measurements of the global properties of ClJ1226.9+3332; we find kT = 10.4± 0.6 keV, Z = 0.16± 0.05Z⊙, and M = 5.2 +1.0 −0.8 × 10 M⊙. We obtain profiles of the metallicity, entropy, cooling time and gas fraction, and find a high concentration parameter for the total density profile of the system. The global properties are compared with the local L− T and M− T relations, and we are able to make the first observational test of the predicted evolution of the YX −M500 relation. We find that departures from these scaling relations are most likely caused by an underestimate of the total mass by ∼ 30% in the X-ray hydrostatic mass analysis due to the apparent recent or ongoing merger activity. Subject headings: cosmology: observations – galaxies: clusters: individual: (ClJ1226.9+3332) – galaxies: clusters: general – galaxies: high-redshift galaxies: clusters – intergalactic medium – X-rays: galaxies