Three-dimensional simulation of large-scale structure in the Universe

Abstract

Three-dimensional numerical simulations of the nonlinear growth of adiabatic perturbations in collisionless matter demonstrate that a cellular structure develops in the Universe. This dark matter collapses into interconnecting dense regions surrounding large voids, or low density regions. The models presented here were done with a cloud-in-cell (CIC) code using a very large number, nearly 9 × 105, of clouds. Such a large number of clouds provides adequate coverage of the voids, eliminates spurious clumping in both the high- and low-density regions, and is a significant improvement over earlier three-dimensional simulations of the cellular structure. We consider here both high (Ω0 = 1.07) and low (Ω0 = 0.1) density models. Our simulations clearly show that the interconnecting dense regions contain both filamentary and flat, pancake-shaped structures. Furthermore, the interactions among neighbouring structures are important and produce matter flows towards the dense intersections. The low-density voids which develop are approximately spherically symmetric in shape. As the voids expand, they collide and intersect. The covariance function ξ(R) has a power law form at small radii, with anticorrelation found just beyond the break and no sizeable features at larger radii.