Simulating Cosmic Structure Formation

TL;DR

This paper reviews cosmological simulation techniques, highlighting their application in modeling large-scale structure formation, galaxy evolution, and the intergalactic medium, emphasizing the Lyman-alpha forest as a key observational test.

Contribution

It provides a comprehensive overview of simulation methods and their success in reproducing observed cosmic structures and phenomena, especially in the high redshift universe.

Findings

Collisionless N-body simulations reproduce large-scale galaxy distribution patterns.

Hydrodynamic simulations form dense cold gas clumps similar to galaxies.

Models predict high redshift galaxies with significant star formation rates.

Abstract

We describe cosmological simulation techniques and their application to studies of cosmic structure formation, with particular attention to recent hydrodynamic simulations of structure in the high redshift universe. Collisionless N-body simulations with Gaussian initial conditions produce a pattern of sheets, filaments, tunnels, and voids that resembles the observed large scale galaxy distribution. Simulations that incorporate gas dynamics and dissipation form dense clumps of cold gas with sizes and masses similar to the luminous parts of galaxies. Models based on inflation and cold dark matter predict a healthy population of high redshift galaxies, including systems with star formation rates of 20 M_{\sun}/year at z=6. At z~3, most of the baryons in these models reside in the low density intergalactic medium, which produces fluctuating Lyman-alpha absorption in the spectra of background quasars. The physical description of this ``Lyman-alpha forest'' is particularly simple if the absorption spectrum is viewed as a 1-dimensional map of a continuous medium instead of a collection of lines. The combination of superb observational data and robust numerical predictions makes the Lyman-alpha forest a promising tool for testing cosmological models.