Correlations between the virial parameters of groups of galaxies

By using two samples of groups of galaxies, revised and selected by Rood and Dickel, we have investigated the significance of the correlations between the virial parameters of galaxy groups. Taking into account observational selection effects present in the two samples, together with statistical and observational uncertainties, we show that only the intrinsic correlation between the luminosity L and the velocity dispersion V is required to explain all the observed correlations. There is no serious ground for stating that the virial radius correlates with both velocity dispersion and luminosity. We also show that the observed slope of the log L-log V relation is considerably smaller than the true slope, while the contrary holds for the log M/L-log V relation. Subject heading: cosmology: galaxies: clusters of