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The evolution of the cluster X-ray scaling relations in the Wide Angle ROSAT Pointed Survey sample at 0.6 < z < 1.0
Authors:B J Maughan †  L R Jones  H Ebeling  C Scharf
Institution:School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT;Harvard–Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02140, USA;Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA;Columbia Astrophysics Laboratory, MC 5247, 550 West 120th St, New York, NY 10027, USA
Abstract:The X-ray properties of a sample of 11 high-redshift  (0.6 < z < 1.0)  clusters observed with Chandra and/or XMM–Newton are used to investigate the evolution of the cluster scaling relations. The observed evolution in the normalization of the   L – T , M – T , M g– T   and M – L relations is consistent with simple self-similar predictions, in which the properties of clusters reflect the properties of the Universe at their redshift of observation. Under the assumption that the model of self-similar evolution is correct and that the local systems formed via a single spherical collapse, the high-redshift L – T relation is consistent with the high- z clusters having virialized at a significantly higher redshift than the local systems. The data are also consistent with the more realistic scenario of clusters forming via the continuous accretion of material.
The slope of the L – T relation at high redshift  ( B = 3.32 ± 0.37)  is consistent with the local relation, and significantly steeper than the self-similar prediction of   B = 2  . This suggests that the same non-gravitational processes are responsible for steepening the local and high- z relations, possibly occurring universally at   z ? 1  or in the early stages of the cluster formation, prior to their observation.
The properties of the intracluster medium at high redshift are found to be similar to those in the local Universe. The mean surface-brightness profile slope for the sample is  β= 0.66 ± 0.05  , the mean gas mass fractions within   R 2500( z )  and   R 200( z )  are  0.069 ± 0.012  and  0.11 ± 0.02  , respectively, and the mean metallicity of the sample is  0.28 ± 0.11 Z  .
Keywords:galaxies: clusters: general  galaxies: high-redshift  intergalactic medium  cosmology: observations  X-rays: galaxies
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