Non-Linear Clustering in the Cold+Hot Dark Matter Model

Abstract

We use high resolution PM N-body simulations to follow the development of non-linear clustering in a flat Universe, dominated by Cold + Hot Dark Matter (CHDM) with 60% of CDM, 30% of HDM and 10% of baryons; a simulation box of 100 Mpc a side ($h=0.5$) is used. We analyze two CHDM simulations with $b =1.5$ (COBE normalization). We also compare them with CDM simulations with $b=1.5$ and $b=1$. We evaluate high-order correlation functions and the void-probability-function (VPF). Correlation functions are obtained both from counts in cells and counts of neighbors. The analysis is made for DM particles and for galaxies, identified as massive halos in the evolved density field. We also check the effects of dynamical evolution and redshift space distortions. We find that clustering of DM particles exhibits deviations from the hierarchical scaling, which decrease somewhat in redshift space. Galaxies follow hierarchical scaling far more closely, with coefficients S_3=2.5 and S_4=7.5, in general agreement with observational results, just marginally affected by redshift distortions and on the choices for the initial spectra. The hierarchical scaling of galaxy clustering is confirmed by the VPF analysis and in all the cases considered a good agreement with observational results is obtained.