相关论文: Constraining Omega with Cluster Evolution
We present constraints on the mean matter density, Omega_m, the normalization of the density fluctuation power spectrum, sigma_8, and the dark-energy equation-of-state parameter, w, obtained from measurements of the X-ray luminosity…
We use the observed evolution of the galaxy cluster X-ray integral temperature distribution function between z=0.05 and z=0.32 in an attempt to constrain the value of the density parameter, Omega_0, for both open and spatially-flat…
We propose that observations of super-massive galaxies contain cosmological constraining power similar to conventional cluster cosmology, and we provide promising indications that the associated systematic errors are comparably easier to…
Elliptical and S0 galaxies dominate the galaxy population in nearby rich clusters such as Coma. Studies of the evolution of the colors, M/L ratios, and line indices of early-type galaxies indicate that they have been a highly homogeneous,…
We argue that there has been substantial evolution in the ellipticity of rich galaxy clusters between 0 < z < 0.1, and suggest that this is additional evidence for a low matter-density Universe.
I show that three independent methods utilizing clusters of galaxies - cluster dynamics and mass-to-light ratio, baryon fraction in clusters, and cluster evolution - all indicate the same robust result: the mass-density of the universe is…
The mass function of galaxy clusters is a powerful tool to constrain cosmological parameters, e.g., the mass fluctuation on the scale of 8 h^{-1} Mpc, sigma_8, and the abundance of total matter, Omega_m. We first determine the scaling…
We investigate the formation of clusters of galaxies in an expanding universe using a new code that regrids at a region of high density. In particular we investigate two models for the initial conditions, both with the standard CDM power…
We investigate the redshift evolution of the matter density parameter, $\Omega_m(z)$, using galaxy cluster gas mass fraction measurements combined with cosmic chronometer $H(z)$ data and type Ia supernova luminosity distances. Our approach…
The clustering of galaxies relative to the mass distribution declines with time because: first, nonlinear peaks become less rare events; second, the densest regions stop forming new galaxies because gas there becomes too hot to cool and…
We study the clustering of the mass distribution in COBE-normalized open and flat CDM models using large N-body simulations. With an age of the universe of 14 Gyr (12 Gyr) for the flat (open) models and a baryon density fixed by…
We investigate the linear amplitude of mass fluctuations in the universe, $\sigma_8$, and the present mass density parameter of the Universe, $\Omega_\mathrm{m}$, from the statistical strong gravitational lensing. We use the two populations…
Tidal forces acting on galaxies in clusters lead to a strong dynamical evolution. In order to quantify the amount of evolution, I run self-consistent N-body simulations of disk galaxies for a variety of models in the hierarchically forming…
We use current observations on the number statistics of gravitationally lensed optical arcs towards galaxy clusters to derive an upper limit on the cosmological mass density of the Universe. The gravitational lensing statistics due to…
The CNOC1 cluster survey measures Omega_M via Oort's method, Omega_M= M/L x j/rho_c, where M/L is the field mass-to-light ratio, j is the field luminosity density and rho_c is the closure density. A wide range of potential systematic…
A precise determination of the mass function is an important tool to verify cosmological predictions of the $\Lambda$CDM model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been…
The geometry of Freedman-Roberston-Walker cosmological models is fixed by the mass density parameter, Omega_M, and the cosmological constant, Omega_Lambda. The classical volume-redshift cosmological relation is a sensitive…
We apply a unique gas fraction estimator to published X-ray cluster properties and we compare the derived gas fractions of observed clusters to simulated ones. The observations are consistent with a universal gas fraction of…
In hierarchical cosmologies the evolution of galaxy clustering depends both on cosmological quantities such as Omega and Lambda, which determine how dark matter halos form and evolve, and on the physical processes - cooling, star formation…
We derive correlations between X-ray temperature, luminosity, and gas mass for a sample of 22 distant, z>0.4, galaxy clusters observed with Chandra. We detect evolution in all three correlations between z>0.4 and the present epoch. In…