We determine the distances to the z \simeq 0.55 galaxy clusters MS 0451.6 - 0305 and Cl 0016 + 16 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 \mbox { $ \Omega _ { M } $ } = 0.3 , \mbox { $ \Omega _ { \Lambda } $ } = 0.7 cosmology , these distances imply a Hubble constant of 63 ^ { +12 } _ { -9 \phantom { 0 } } { } ^ { +21 } { } _ { -21 } km s ^ { -1 } Mpc ^ { -1 } , where the uncertainties correspond to statistical followed by systematic at 68 % confidence .
The best fit H _ { \circ } is 57 km s ^ { -1 } Mpc ^ { -1 } for an open \mbox { $ \Omega _ { M } $ } = 0.3 universe and 52 km s ^ { -1 } Mpc ^ { -1 } for a flat \mbox { $ \Omega _ { M } $ } = 1 universe .