Non-Gaussian initial conditions in cosmological N-body simulations — I. Space-uncorrelated models

Abstract

Summary Results are reported on N-body simulations of the large-scale structure of the Universe starting from non-Gaussian, space-uncorrelated, initial conditions: specifically, we consider two hierarchical models and the lognormal statistics for the initial probability distribution. These models share two common properties: they fulfil the positive mass constraint (δM ≥ − 1) and they have positive skewness (〈δM3〉>0). The resulting distributions, both in space and velocity, are analysed by means of many statistical tests, and compared with an evolved reference Poisson model. The different starting conditions keep their effects after many expansion times as shown in particular by the cluster analysis and by the quadrupole statistics: the evolved nonGaussian distributions show the existence of elongated and/or flattened configurations in excess of the evolved Poisson model. The velocity field, analysed in terms of the cosmic Mach number, does not reveal relevant changes with respect to the initially Gaussian model. In general we find that the different models are better discriminated by their geometry (like the percolation curve and the amount of filamentariness) than by their clustering properties.