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Date and Time of the Query: 2019-04-20 T17:43:25 PDT
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For refcode 1999ApJ...524...22W:
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1999ApJ...524...22W The L_X_-T and L_X_-{sigma} Relationships for Galaxy Clusters Revisited Xiang-Ping Wu and Yan-Jie Xue Beijing Astronomical Observatory and National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, Peoples Republic of China and Li-Zhi Fang Department of Physics, University of Arizona, Tucson, AZ 85721 Received 1998 October 30; accepted 1999 May 30 ABSTRACT The relationships between the X-ray-determined bolometric luminosity, LX, the temperature, T, of the intracluster gas, and the optical measured velocity dispersion, {sigma}, of the cluster galaxies are updated for galaxy clusters using the largest sample of 256 clusters drawn from literature. The newly established relationships, based on the doubly weighted orthogonal distance regression (ODR) method, are justified by both their self-consistency and co-consistency, which can then be used to test the theoretical models of cluster formation and evolution. The observationally determined L_X_-T and L_X_-{sigma} relationships, L_X_ is proportional to T^2.72+/-0.05^ is proportional to {sigma}^5.24+/-0.29^, are marginally consistent with those predicted by the scenario in which both intracluster gas and galaxies are in isothermal and hydrostatic equilibrium with the underlying gravitational potential of clusters. A comparison between these observed and predicted L_X_-T relationships also suggests that the mean cluster baryon fraction, f_b_, remains approximately constant among different clusters, f_b_ ~ 0.17, which gives rise to a low mass density universe of {OMEGA}_m_ ~ 0.3. Subject headings: cosmology: observations-galaxies: clusters: general-X- rays: galaxies
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