The Cluster M/L and the Value of Omegam
Abstract
From an up-to-date compilation of ACO cluster redshifts and velocity dispersions we extract a homogeneous sample of 459 clusters with robust velocity dispersion. Using the virial theorem to estimate cluster masses, and a correlation between Abell galaxy counts and R-band luminosity, we find a median M/LR of 174 h50 Msun/Lsun. However, if we correct the virial masses according to the X-ray vs. virial mass correlation, as derived from our analysis, we obtain M/LR ~100 h50 Msun/Lsun. These two values of M/L imply a mass content of the Universe of Omegam ~0.26 and 0.15, respectively.
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