Weighing the giants  IV. Cosmology and neutrino mass
Abstract
We employ robust weak gravitational lensing measurements to improve cosmological constraints from measurements of the galaxy cluster mass function and its evolution, using Xray selected clusters detected in the ROSAT AllSky Survey. Our lensing analysis constrains the absolute mass scale of such clusters at the 8 per cent level, including both statistical and systematic uncertainties. Combining it with the survey data and Xray followup observations, we find a tight constraint on a combination of the mean matter density and latetime normalization of the matter power spectrum, σ_{8}(Ω_{m}/0.3)^{0.17} = 0.81 ± 0.03, with marginalized, onedimensional constraints of Ω_{m} = 0.26 ± 0.03 and σ_{8} = 0.83 ± 0.04. For these two parameters, this represents a factor of 2 improvement in precision with respect to previous work, primarily due to the reduced systematic uncertainty in the absolute mass calibration provided by the lensing analysis. Our new results are in good agreement with constraints from cosmic microwave background (CMB) data, both Wilkinson Microwave Anisotropy Probe (WMAP) and Planck (plus WMAP polarization), under the assumption of a flat ΛCDM cosmology with minimal neutrino mass. Consequently, we find no evidence for nonminimal neutrino mass from the combination of cluster data with CMB, supernova and baryon acoustic oscillation measurements, regardless of which allsky CMB data set is used (and independent of the recent claimed detection of B modes on degree scales). We also present improved constraints on models of dark energy (both constant and evolving), modifications of gravity, and primordial nonGaussianity. Assuming flatness, the constraints for a constant dark energy equation of state from the cluster data alone are at the 15 per cent level, improving to ∼6 per cent when the cluster data are combined with other leading probes.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 January 2015
 DOI:
 10.1093/mnras/stu2096
 arXiv:
 arXiv:1407.4516
 Bibcode:
 2015MNRAS.446.2205M
 Keywords:

 cosmological parameters;
 cosmology: observations;
 largescale structure of Universe;
 Xrays: galaxies: clusters;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 10 figures, 5 tables. v3: typo in table A1 corrected