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For refcode 1997ApJ...483...62W:
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1997ApJ...483...62W A Statistical Comparison of Cluster Mass Estimates from Optical/X-Ray Observations and Gravitational Lensing XIANG-PING WU Beijing Astronomical Observatory, Chinese Academy of Science, Beijing 100080, China AND LI-ZHI FANG Department of Physics, University of Arizona, Tucson, AZ 85721 Received 1996 October 21; accepted 1997 January 30 ABSTRACT We present a statistical comparison of three different estimates of cluster mass, namely, the dynamical masses obtained from the velocity dispersion of optical galaxies, the X-ray masses measured from the temperature of X-ray-emitting gas under the assumption of isothermal hydrostatic equilibrium, and the gravitational lensing masses derived from the strong/weak distortions of background galaxy images. Using a sample of 29 lensing clusters available in literature, we show that the dynamical masses are in agreement with the gravitational lensing masses while the X-ray method has systematically underestimated cluster masses by a factor of 2-3 as compared with the others. These results imply that galaxies indeed trace the gravitational potential of their clusters and that there is no bias between the velocities of the dark matter particles and the galaxies in clusters. The X-ray cluster mass discrepancy probably arises from the simplification in the models for the X-ray gas distribution and dynamical evolution. Subject headings: cosmology: theory-galaxies: clusters: general - galaxies: fundamental parameters-gravitational lensing -X-rays: galaxies
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