Streaming velocities as a dynamical estimator of Omega

It is well known that estimating the mean pairwise velocity of galaxies v(1 2) from the redshift space galaxy correlation function is difficult because this method is highly sensitive to the assumed model of the pairwise veloc ity dispersion. Here we propose an alternative method to estimate v(12) dir ectly from peculiar velocity samples, which contain redshift-independent di stances as well as galaxy redshifts. In contrast to other dynamical measure s which determine beta = Omega(0.6)sigma(8), this method can provide an est imate of Omega(0.6)sigma(8)(2) for a range of sigma(8), where Omega is the cosmological density parameter, while a, is the standard normalization for the power spectrum of density fluctuations. We demonstrate how to measure t his quantity from realistic catalogs.