Precise Measurements of the Hubble Constant and Structures of Clusters of Galaxies

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On the theoretical and observational investigations of the structure of clusters of galaxies, we established a new model of intracluster gas distribution. The fitting of our model with observational data is considerably better than the isothermal beta model, and the cluster mass distribution derived by using our model has a tendency to solve the discrepancy between the values obtained from the X-ray and the gravitational-lensing data. We made also the analysis of X-ray data of A2029 obtained with XMM-Newton. A2029 is a typical cD-type cluster of galaxies having a giant cD galaxy in the center. Although the data analysis of this cluster is still going on, many interesting results have been obtained. For example, in the central region a two-temperature model is preferred to some ordinary single temperature models.On the measurement of the Hubble constant, Ho, using the Sunyaev-Zel'dovich effect, we succeeded to obtain available data for five distant (0.143【less than or equal】z【less than or equal】0.282) clusters of galaxies observed with ROSAT, ASCA (X-ray) and the Ryle Telescope (radio). The obtained value of Ho for these clusters are considerably scattered, and their mean value is 66+11/-10 (random) +9/-8 (systematic) km/s/Mpc for a ACDM (ΩM=0.3, ΩA=0.7) flat universe. This value of Ho is slightly less than the value of Ho=71±2 km/s/Mpc obtained from WMAP observations of the cosmic microwave background radiation, but they are in good agreement within their errors.