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

We present a spatially resolved analysis of the temperature and gas density profiles in six relaxed galaxy clusters at z = 0.4-0.54 using long-exposure Chandra observations. We derive the total cluster masses within the radius r₅₀₀, 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 3 keV < T < 14 keV. The observed evolution of the M-T relation, relative to the low-redshift references from the Chandra sample of Vikhlinin et al., follows M₅₀₀/T^3/2 ∝ E(z)^-α, where we measure α = 1.02 ± 0.20 and 1.33 ± 0.20 for the spectroscopic and gas mass-weighted temperatures, respectively. Both values are in agreement with the expected self-similar evolution, α = 1. Assuming that the cluster mass for a given temperature indeed evolves self-similarly, the derived slopes, γ, of the high-redshift M-T relation, E(z)M₅₀₀ ∝ T^γ, are γ = 1.55 ± 0.14 for T_spec and γ = 1.65 ± 0.15 for T_mg. Our results show that both the shape and evolution of the cluster M-T relation at z ≃ 0.5 are close to predictions of the self-similar theory.