Superlarge-scale structure in N-body simulations

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. A wall-like superlarge-scale structure with parameters similar to the observed one is found for the OCDM and Lambda CDM models with Omega(m)h = 0.2-0.3. In these simulations, the rich structure elements with a typical value for the largest extension of similar to(30 - 50)h(-1) Mpc incorporate similar to 40 per cent of matter with overdensity of about 10 above the mean. These rich elements are formed by the anisotropic non-linear compression of sheets with an original size of similar to(15-25)h(-1) Mpc. They surround low-density regions with a typical diameter similar to(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 Omega(m) = 1 in CDM with Harrison-Zeldovich or tilted power spectra cannot reproduce the characteristics of the observed galaxy distribution because of the very strong disruption of the rich structure elements. Another model with a broken scale-invariant initial power spectrum (BCDM) does not show enough matter concentration in the rich structure elements.