Chandra Sample of Galaxy Clusters at z=0.4-0.55: Evolution in the Mass-Temperature Relation

Abstract

We present spatially-resolved analysis of the temperature and gas density profiles in 6 relaxed galaxy clusters at z = 0.4-0.54 using long-exposure Chandra observations. We derived the total cluster masses within the radius r_500 assuming hydrostatic equilibrium but without assuming isothermality of the intracluster gas. Together with a similar study based on the XMM-Newton observations (Kotov & Vikhlinin), we obtained the mass and temperature measurements for 13 galaxy clusters at 0.4<z<0.7 spanning a temperature interval of 3keV<T<14keV. The observed evolution of the M-T relation, relative to the low-redshift references from the Chandra sample of Vikhlinin et al., follows M_500/T^{3/2} ~ E(z)^alpha, where we measure alpha=1.02\pm0.20 and alpha=1.33\pm0.20 for the spectroscopic and gas mass-weighted temperatures, respectively. Both values are in agreement with the expected self-similar evolution, alpha=1. Assuming that the cluster mass for given temperature indeed evolves self-similarly, the derived slopes, $\gamma$, of the high-redshift M-T relation, E(z)M_500 ~ T^gamma, are gamma=1.55\pm0.14 for T_spec and gamma=1.65\pm0.15 for T_mg. Our results show that both the shape and evolution of the cluster M-T relation at z~0.5 is close to predictions of the self-similar theory.