ChandraSample of Nearby Relaxed Galaxy Clusters: Mass, Gas Fraction, and Mass‐Temperature Relation

We present gas and total mass profiles for 13 low-redshift, relaxed clustersspanning a temperature range 0.7-9 keV, derived from all available Chandra dataof sufficient quality. In all clusters, gas temperature profiles are measuredto large radii (Vikhlinin et al.) so that direct hydrostatic mass estimates arepossible to nearly r_500 or beyond. The gas density was accurately traced tolarger radii; its profile is not described well by a beta-model, showingcontinuous steepening with radius. The derived rho_tot profiles and theirscaling with mass generally follow the Navarro-Frenk-White model withconcentration expected for dark matter halos in LambdaCDM cosmology. In theinner region (r<0.1r_500), the gas density and temperature profiles exhibitsignificant scatter and trends with mass, but they become nearly self-similarat larger radii. Correspondingly, we find that the slope of themass-temperature relation for these relaxed clusters is in good agreement withthe simple self-similar behavior, M_500 ~ T^alpha, where alpha=(1.5-1.6)+-0.1,if the gas temperatures are measured excluding the central cool cores. Thenormalization of this M-T relation is significantly, by =~ 30%, higher thanmost previous X-ray determinations. We derive accurate gas mass fractionprofiles, which show increase both with radius and cluster mass. The enclosedf_gas profiles within r_2500 =~ 0.4 r_500 have not yet reached any asymptoticvalue and are still far (by a factor of 1.5-2) from the Universal baryonfraction according to the CMB observations. The f_gas trends become weaker andits values closer to Universal at larger radii, in particular, in sphericalshells r_2500

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