AAS 205th Meeting, 9-13 January 2005
Session 148 Large Scale Structure
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[148.08] Cosmological Implications of Galaxy Cluster Evolution and Substructure

B. C. Hart, D. A. Buote, P. J. Humphrey (University of Califorina, Irvine), R. Valdarnini (Sc. Intl. Sup. di Studi Avanzanti)

We examined the sensitivity of the spatial morphologies of galaxy clusters, as observed in X-rays, to the cosmological parameters \Omegam,0, \Omega\Lambda, and \sigma8 (\emph{rms} mass fluctuations in a sphere of radius 8h-1 Mpc). Morphologies of galaxy clusters provide constraints on the dynamical state of these systems. We observed sources in a flux-limited sample of 50 nearby (i.e. 0.015\le{z}\le0.2) galaxy clusters with \emph{ROSAT} and compared these with results from high-resolution N-body simulations incorporating TREESPH gas hydrodynamics. The observational sample was derived from the HIFLUGCS sample of Reiprich and Böhringer (2002) and has a lower X-ray flux limit in the 0.1-2.4 keV band of 2.0\times 10-11 erg s-1 cm-2 to ensure we are in the cluster regime. Variants of the standard cold dark matter (CDM) models are considered having different spatial curvatures and normalizations: SCDM (\Omegam,0 = 1, \Omega\Lambda=0, \sigma8=1), OCDM (\Omegam,0 = 0.3, \Omega\Lambda=0, \sigma8=0.85), LCDM07 (\Omegam,0 = 0.3, \Omega\Lambda=0.7, \sigma8=0.7) and LCDM09 (\Omegam,0 = 0.3, \Omega\Lambda=0.7, \sigma8=0.9). Cluster X-ray morphologies are quantified using the power ratios (PRm) of Buote and Tsai (1996). We compared the observations and simulations at an aperture of 0.5h70-1 Mpc. The LCDM07 model, with \sigma8=0.7, is indistinguishable from the SCDM model. The comparisons with observations disfavor OCDM as opposed to LCDM07 and SCDM. This indicates \Omegam,0+\Omega\Lambda=1, independently of the WMAP (2003) first CMB results.

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