A comparison of the evolution of density fields in perturbation theory and numerical simulations - II. Counts-in-cells analysis.

Baugh, C.M.; Gaztañaga, E.; Efstathiou, G.

Abstract

We present a detailed comparison of the predictions of perturbation theory (PT) for the averaged J-point correlation functions, ξJξJ, with the results of numerical simulations of gravitational clustering. We carry out a systematic analysis of this method using ensembles of simulations with different numbers of particles, different box sizes, and different particle arrangements and clustering amplitudes in the initial conditions. We estimate ξJξJ, for J=2-10, from moments of counts in cells. We find significant non-linear effects in the variance, J=2, even at scales as large as R∼30h−1R∼30h−1 Mpc. Perturbation theory gives remarkable agreement at large scales, where ξ2≲1ξ2≲1, with the measured hierarchical amplitudes SJ=ξ¯J/ξ¯J−12SJ=ξ¯J/ξ¯2J−1. We follow the evolution of ξJξJ in time and find that, at large scales, R≳ 7h−1R≳ 7h−1 Mpc, at least during the last three expansion factors, the SJSJ do not change with time, which is as predicted by PT theory, despite the fact that the ξJξJ have evolved by large factors, ≃10J−1≃10J−1. We illustrate how these results can be applied to interpret the clustering in galaxy surveys and conclude that the observed hierarchical pattern in the APM Survey is compatible with gravitational evolution in unbiased, initially Gaussian, models.

Citation

Baugh, C., Gaztañaga, E., & Efstathiou, G. (1995). A comparison of the evolution of density fields in perturbation theory and numerical simulations - II. Counts-in-cells analysis. Monthly Notices of the Royal Astronomical Society, 274(4), 1049-1070. https://doi.org/10.1093/mnras/274.4.1049

• Journal Article Type: Article
• Publication Date: 1995-06
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 274
• Issue: 4
• Pages: 1049-1070
• DOI: https://doi.org/10.1093/mnras/274.4.1049
• Public URL: https://durham-repository.worktribe.com/output/1619094