Superlarge-Scale Structure in N-body Simulations

Abstract

The simulated matter distribution on large scales is studied using core-sampling, cluster analysis, inertia tensor analysis, and minimal spanning tree techniques. Seven simulations in large boxes for five cosmological models with COBE normalized CDM-like power spectra are studied. The wall-like Super Large Scale Structure with parameters similar to the observed one is found for the OCDM and LCDM models with Omega_m h = 0.3 & 0.245. In these simulations, the rich structure elements with a typical value for the largest extension of \~(30 - 50) h^-1 Mpc incorporate ~40% of matter with overdensity of about 10 above the mean. These rich elements are formed due to the anisotropic nonlinear compression of sheets with original size of ~(15 - 25) h^{-1} Mpc. They surround low-density regions with a typical diameter ~(50 - 70) h^{-1} Mpc. The statistical characteristics of these structures are found to be approximately consistent with observations and theoretical expectations. The cosmological models with higher matter density Ω_m=1 in CDM with Harrison-Zeldovich or tilted power spectra cannot reproduce the characteristics of the observed galaxy distribution due to the very strong disruption of the rich structure elements. Another model with a broken scale invariant initial power spectrum (BCDM) shows not enough matter concentration in the rich structure elements.