VELOCITY-FIELDS IN NON-GAUSSIAN COLD DARK-MATTER MODELS

We analyse the large-scale velocity field obtained by N-body simulatio ns of cold dark matter (CDM) models with non-Gaussian primordial densi ty fluctuations, considering models with both positive and negative pr imordial skewness in the density fluctuation distribution. We study th e velocity probability distribution and calculate the dependence of th e bulk flow, one-point velocity dispersion and cosmic Mach number on t he filtering size. We find that the sign of the primordial skewness of the density field provides poor discriminatory power on the evolved v elocity field. All non-Gaussian models considered here tend to have lo wer velocity dispersion and bulk flow than the standard Gaussian CDM m odel, while the cosmic Mach number turns out to be a poor statistic in characterizing the models. We also compare the large-scale velocity f ield of a composite sample of optically selected galaxies as described by the Local Group properties, bulk flow, velocity correlation functi on and cosmic Mach number with the velocity field of mock catalogues e xtracted from the N-body simulations. The comparison does not clearly single out the best model: the standard Gaussian model is, however, ma rginally preferred by the maximum likelihood analysis.