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We determine the distances to the z~0.55 galaxy clusters MS0451 and CL0016 from a maximum likelihood joint fit to interferometric Sunyaev-Zel'dovich effect (SZE) and X-ray observations. We model the intracluster medium (ICM) using a spherical isothermal beta-model. We quantify the statistical and systematic uncertainties inherent to these direct distance measurements, and we determine constraints on the Hubble parameter for three different cosmologies. For an OmegaM=0.3, OmegaL=0.7 cosmology, these distances imply a Hubble constant of 63(+12/-9),(+21/-21)km/s/Mpc, where the uncertainties correspond to statistical followed by systematic at 68% confidence. The best fit Ho is 57km/s/Mpc for an open OmegaM=0.3 universe and 52km/s/Mpc for a flat OmegaM=1 universe. |
