Universal Non-Gaussian Initial Conditions for N-body Simulations

TL;DR

This paper introduces an efficient modal formalism for generating arbitrary non-Gaussian initial conditions in N-body simulations, enabling the creation of complex primordial spectra and improving simulation accuracy.

Contribution

It presents a novel separable modal approach that efficiently generates non-Gaussian initial conditions, including non-separable bispectra and diagonal-free trispectra, for the first time.

Findings

Efficient generation of non-Gaussian initial conditions

Capability to produce non-separable bispectra

Reconstruction of spectra from realisations for validation

Abstract

In this paper we present the implementation of an efficient formalism for the generation of arbitrary non-Gaussian initial conditions for use in N-body simulations. The methodology involves the use of a separable modal approach for decomposing a primordial bispectrum or trispectrum. This approach allows for the far more efficient generation of the non-Gaussian initial conditions already described in the literature, as well as the generation for the first time of non-separable bispectra and the special class of diagonal-free trispectra. The modal approach also allows for the reconstruction of the spectra from given realisations, a fact which is exploited to provide an accurate consistency check of the simulations.