Transients from Initial Conditions Based on Lagrangian Perturbation Theory in $N$-body Simulations III: The Case of GADGET-2 Code

TL;DR

This paper investigates the impact of third-order Lagrangian perturbation (3LPT) on initial conditions in GADGET-2 cosmological simulations, comparing non-Gaussianity to lower-order methods to improve prediction accuracy.

Contribution

It introduces the application of 3LPT to GADGET-2 initial conditions and evaluates its effects on matter density field statistics, particularly non-Gaussianity.

Findings

3LPT affects the statistical properties of initial conditions.

2LPT remains valid for certain cosmological predictions.

Comparison shows differences in non-Gaussianity between perturbation orders.

Abstract

In modern cosmology, the precision of the theoretical prediction is increasingly required. In cosmological $N$-body simulations, the effect of higher-order Lagrangian perturbation on the initial conditions appears in terms of statistical quantities of matter density field. We have considered the effect of third-order Lagrangian perturbation (3LPT) on the initial conditions, which can be applied to Gadget-2 code. Then, as statistical quantities, non-Gaussianity of matter density field has been compared between cases of different order perturbations for the initial conditions. Then, we demonstrate the validity of the initial conditions with second-order Lagrangian perturbation (2LPT).