paper

Chandra X-ray analysis of the massive high-redshift galaxy clusters ClJ1113.1-2615 and ClJ0152.7-1357

arXiv:astro-ph/0301218 · doi:10.1086/368151

Abstract

We present an analysis of Chandra observations of two high-redshift clusters of galaxies, ClJ1113.1-2615 at z=0.725 and ClJ0152.7-1357 at z=0.833. We find ClJ1113 to be relaxed with kT=4.3^{+0.5}_{-0.4}keV and a mass (within the virial radius) of 4.3^{+0.8}_{-0.7}*10^{14}Msol. ClJ0152, by contrast, is resolved into a northern and southern subcluster, each massive and X-ray luminous, in the process of merging. The temperatures of the subclusters are found to be 5.5^{+0.9}_{-0.8}keV and 5.2^{+1.1}_{-0.9}keV respectively, and their respective masses are 6.1^{+1.7}_{-1.5}*10^{14}Msol and 5.2^{+1.8}_{-1.4}*10^{14}Msol within the virial radii. 2D modelling of the X-ray surface brightness reveals excess emission between the subclusters; suggestive, but not conclusive evidence of a shock front. We make a first attempt at measuring the cluster M-T relation at z~0.8, and find no evolution in its normalisation, supporting the previous assumption of an unevolving M-T relation. We also find little or no evolution in the L-T relation, the gas fraction-T relation, the beta-T relation or the metallicity. These results suggest that, in at least some massive clusters, the hot gas was in place, and containing its metals, at z~0.8. We also highlight the need to correct for the degradation of the Chandra ACIS low energy quantum efficiency in high-redshift cluster studies when the low energy absorption is often assumed to be the Galactic value, rather than measured.

55 pages, 16 figures, Latex. Accepted for publication in Astrophysical Journal. Author address corrected, reference added. Error in Eqn 3 corrected - small changes to gas mass values in text and Fig 15. Conclusions unchanged

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