Key points are not available for this paper at this time.
This is the second in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. The data set employed here consists of Chandra observations of 40 such clusters, identified in a comprehensive search of the Chandra archive for hot (kT ∼ 5 keV), massive, morphologically relaxed systems, as well as high-quality weak gravitational lensing data for a subset of these clusters. Here we present cosmological constraints from measurements of the gas mass fraction, fgas, for this cluster sample. By incorporating a robust gravitational lensing calibration of the X-ray mass estimates, and restricting our measurements to the most self-similar and accurately measured regions of clusters, we significantly reduce systematic uncer-tainties compared to previous work. Our data for the first time constrain the intrinsic scatter in fgas, 7.4±2.3 per cent in a spherical shell at radii 0.8–1.2 r2500 ( ∼ 1/4 of the virial radius), consistent with the expected level of variation in gas depletion and non-thermal pressure for relaxed clusters. From the lowest-redshift data in our sample, five
Mantz et al. (Fri,) studied this question.