The Large-Scale Structure of the Universe in Skewed Cold Dark Matter Models

We present results from N-body simulations of the clustering properties of the universe in a cubic box of size 260h-1 Mpc, within a cold dark matter (CDM) cosmology with skewed distributions for initial adiabatic density perturbations \u3b4M. We consider two non-Gaussian models, Chi-squared and Lognormal, where the primordial gravitational potential is obtained from a non-linear transformation on a Gaussian random field. Our procedure yields for each model two primordial density distributions with opposite skewness \u3b43M. The gravitational evolution and the present statistical properties of our simulations are strongly sensitive to the sign of the initial skewness. Skew-positive simulations produce a highly lumpy distribution with little power on large scales. Skew-negative simulations, on the contrary, evolve towards a cellular structure with high power on large scales, showing, in many respects, better agreement with observations than the standard CDM model. Giving up the random-phase hypothesis for primordial perturbations seems then a viable possibility to reproduce the large-scale properties of the universe; such a possibility is further motivated by many physical models either within the inflationary dynamics or phase transitions in the early universe