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Session 42 - Structure and Evolution of The Universe.
Display session, Tuesday, June 09
Atlas Ballroom,

[42.07] Cluster Masses at z\sim0.3 from X-ray observations

A. D. Lewis, E. Ellingson (U. Colorado), S. L. Morris (DAO), R. G. Carlberg (U. Toronto)

Results are presented from the analysis of ROSAT HRI and PSPC observations of the CNOC subsample of the EMSS high redshift galaxy clusters. Surface brightness profiles of 13 clusters with 0.17 < z < 0.55 are constructed and fit to isothermal \beta models. Where possible, we make a unique combination of both the HRI and PSPC data to improve the fit. Cooling flows and their affect on the data are discussed. We derive total X-ray masses which are compared with both the dynamical masses obtained from galaxy velocities and the projected masses from published gravitational lensing studies. We find no systematic bias factor between X-ray and optical methods across the sample, although individual clusters exhibit mass discrepancies up to a factor of 2. Gravitational lensing masses are observed to be systematically slightly higher than X-ray derived masses across the sample. Strong lensing measurements at a few core radii appear to be somewhat more discrepant (factors > 2 for many clusters) than weak lensing masses calculated at larger radii (factors of \sim 1.5). X-ray derived cluster gas masses are calculated, from which we obtain a cluster baryon fraction of \sim4%h^-3/2_100, yielding Ømega_0\sim0.3. In addition, we find that the \beta-discrepancy can be resolved for these data using the observed average galaxy density profile.

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