The Cosmic Code Comparison Project

TL;DR

This paper compares multiple cosmological simulation codes focusing on nonlinear regimes, halo properties, and introduces ParaView as a tool to facilitate code validation, ensuring simulation accuracy matches observational demands.

Contribution

It extends a previous code comparison to include five additional codes and introduces ParaView for easier analysis of simulation data.

Findings

Codes agree within 10% for power spectrum and mass function

Halo profiles and counts vary with local density

ParaView simplifies complex simulation data analysis

Abstract

Current and upcoming cosmological observations allow us to probe structures on smaller and smaller scales, entering highly nonlinear regimes. In order to obtain theoretical predictions in these regimes, large cosmological simulations have to be carried out. The promised high accuracy from observations make the simulation task very demanding: the simulations have to be at least as accurate as the observations. This requirement can only be fulfilled by carrying out an extensive code validation program. The first step of such a program is the comparison of different cosmology codes including gravitation interactions only. In this paper we extend a recently carried out code comparison project to include five more simulation codes. We restrict our analysis to a small cosmological volume which allows us to investigate properties of halos. For the matter power spectrum and the mass function, the previous results hold, with the codes agreeing at the 10% level over wide dynamic ranges. We extend our analysis to the comparison of halo profiles and investigate the halo count as a function of local density. We introduce and discuss ParaView as a flexible analysis tool for cosmological simulations, the use of which immensely simplifies the code comparison task.