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Baryon fraction in clusters, combined with constraints from primordial nucleosynthesis is currently used to provide a robust upper limit on the cosmological density parameter $\Omega_0$. Current analyses lead to gas fractions at virial…

Astrophysics · Physics 2009-11-06 R. Sadat , A. Blanchard

Cluster abundance measurements are among the most sensitive probes of the amplitude of matter fluctuations in the universe, which in turn can help constrain other cosmological parameters, like the dark energy equation of state or neutrino…

Astrophysics · Physics 2010-10-27 Rachel Mandelbaum , Uros Seljak

The abundance of rich clusters is a strong constraint on the mass power spectrum. The current constraint can be expressed in the form $\sigma_8 \Omega_m^{\gamma} = 0.5 \pm 0.1$ where $\sigma_8$ is the $rms$ mass fluctuation on 8 $h^{-1}$…

Astrophysics · Physics 2009-09-15 Limin Wang , Paul J. Steinhardt

The number density of galaxy clusters provides tight statistical constraints on the matter fluctuation power spectrum normalization, traditionally phrased in terms of sigma_8, the root mean square mass fluctuation in spheres with radius 8…

Astrophysics · Physics 2011-02-11 J. Patrick Henry , August E. Evrard , Henk Hoekstra , Arif Babul , Andishieh Mahdavi

The mass function of clusters of galaxies is determined from 400 deg^2 of early commissioning imaging data of the Sloan Digital Sky Survey; ~300 clusters in the redshift range z = 0.1 - 0.2 are used. Clusters are selected using two…

Direct observations of the supposedly universal primordial deuterium abundance imply a relatively large baryon density $\Omega_B= (0.019-0.030)h^{-2}$ (95% C.L.). On the other hand, concordance between the previously accepted $^4 He$ and…

Astrophysics · Physics 2009-10-30 S. A. Bludman

We present updated cosmological constraints from measurements of the gas mass fractions ($f_{gas}$) of massive, dynamically relaxed galaxy clusters. Our new data set has greater leverage on models of dark energy, thanks to the addition of…

We test an analytic model for the two-point correlations of galaxy clusters in redshift space using the Hubble Volume N-body simulations. The correlation function of clusters shows no enhancement along the line of sight, due to the lack of…

Astrophysics · Physics 2009-11-06 Nelson D. Padilla , Carlton M. Baugh

We present a new determination of the mass function of galaxy clusters, based on optical virial mass estimates for a large sample of 152 nearby (z\le0.15) Abell-ACO clusters, as provided by Girardi et al. (1998). This sample includes both…

Astrophysics · Physics 2016-08-30 M. Girardi , S. Borgani , G. Giuricin , F. Mardirossian , M. Mezzetti , ;

Several recent studies used the hot gas fraction of galaxy clusters as a standard ruler to constrain dark energy, which provides competitive results compared to other techniques. This method, however, relies on the assumption that the…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-08 Dominique Eckert , Stefano Ettori , Silvano Molendi , Franco Vazza , Stéphane Paltani

We study the properties of X-ray galaxy clusters in four cold dark matter models with different baryon fraction $\Omega_{BM}$ ranging from 5 to 20 per cent. By using an original three-dimensional hydrodynamic code based on the piecewise…

Astrophysics · Physics 2009-10-30 Claudio Gheller , Ornella Pantano , Lauro Moscardini

We propose a new cosmological test of gravity, by using the observed mass fraction of X-ray emitting gas in massive galaxy clusters. The cluster gas fraction, believed to be a fair sample of the average baryon fraction in the Universe, is a…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-23 Baojiu Li , Jian-hua He , Liang Gao

Clusters of galaxies are the most impressive gravitationally-bound systems in the Universe and its abundance (the cluster mass function) is one important statistics to probe the matter density parameter ($\Omega_m$) and the amplitude of…

Astrophysics · Physics 2014-11-18 L. Marassi , J. V. Cunha , J. A. S. Lima

(shortened) We develop and test a method to compute mass and auto-correlation functions of rich clusters of galaxies from linear density fluctuations, based on the formalism of Gaussian peaks (Bardeen et al 1986). The essential, new…

Astrophysics · Physics 2009-10-30 Renyue Cen

We present measurements of the anisotropic galaxy clustering from the Data Release 9 (DR9) CMASS sample of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We analyze the broad-range shape of the monopole and quadrupole…

Context: The evolution of the cluster abundance with redshift is known to be a powerful cosmological constraint when applied to X-ray clusters. Recently, the evolution of the baryon mass function has been proposed as a new variant that is…

Astrophysics · Physics 2009-11-11 S. E. Nuza , A. Blanchard

The number density of rich galaxy clusters still provides the most robust way of normalizing the power spectrum of dark matter perturbations on scales relevant to large-scale structure. We revisit this constraint in light of several recent…

Astrophysics · Physics 2009-09-25 E. Pierpaoli , D. Scott , M. White

(Abriged) We present the analysis of the baryonic content of 52 X-ray luminous galaxy clusters observed with Chandra in the redshift range 0.3-1.273. We use the deprojected X-ray surface brightness profiles and the measured values of the…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-11 S. Ettori , A. Morandi , P. Tozzi , I. Balestra , S. Borgani , P. Rosati , L. Lovisari , F. Terenziani

We derive constraints on the mass-temperature relation of galaxy clusters from their observed luminosity-temperature relation and X-ray temperature function. Adopting the isothermal gas in hydrostatic equilibrium embedded in the universal…

Astrophysics · Physics 2009-11-07 Mamoru Shimizu , Tetsu Kitayama , Shin Sasaki , Yasushi Suto

A complete catalogue of galaxy cluster models can be used to constrain cosmological parameters like $\sigma_8$, the amplitude of the initial density fluctuation spectrum. We focus here on two strong lensing statistics for clusters of…

Astrophysics · Physics 2007-05-23 Eelco van Kampen