Scale Dependence of Halo Bispectrum from Non-Gaussian Initial Conditions in Cosmological N-body Simulations

TL;DR

This paper investigates how the halo bispectrum's shape and scale dependence in cosmological simulations are influenced by non-Gaussian initial conditions, revealing a strong $f_{nl}^2$ scaling and potential for distinguishing inflation models.

Contribution

It provides the first detailed analysis of the halo bispectrum's dependence on non-Gaussianity parameters across scales, shapes, redshifts, and halo masses using large N-body simulations.

Findings

Halo bispectrum strongly depends on shape and scale near squeezed configurations.

Amplitude scales roughly as $f_{nl}^2$, consistent with perturbation theory.

Dependence on $f_{nl}$ is stronger for massive haloes at higher redshifts.

Abstract

We study the halo bispectrum from non-Gaussian initial conditions. Based on a set of large $N$-body simulations starting from initial density fields with local type non-Gaussianity, we find that the halo bispectrum exhibits a strong dependence on the shape and scale of Fourier space triangles near squeezed configurations at large scales. The amplitude of the halo bispectrum roughly scales as $f_nl^2$. The resultant scaling on the triangular shape is consistent with that predicted by Jeong & Komatsu based on perturbation theory. We systematically investigate this dependence with varying redshifts and halo mass thresholds. It is shown that the $f_nl$ dependence of the halo bispectrum is stronger for more massive haloes at higher redshifts. This feature can be a useful discriminator of inflation scenarios in future deep and wide galaxy redshift surveys.