The Effect of Primordial Non--Gaussianity on the Topology of Large-Scale Structure

TL;DR

This study investigates how primordial non-Gaussianity influences the topology of large-scale cosmic structures, using simulations and Minkowski Functionals, revealing effects detectable at certain scales and non-Gaussianity levels.

Contribution

It provides a detailed analysis of the impact of primordial non-Gaussianity on cosmic web topology through simulations and compares results with perturbation theory predictions.

Findings

Analytic formulas agree with simulations for |fNL|<1000 in weakly non-linear regime.

Deviations increase in non-linear regime but overall amplitude remains consistent.

Primordial non-Gaussianity effects become significant with smaller scales and specific fNL values.

Abstract

We study the effect of primordial non-Gaussianity on the development of large-scale cosmic structure using high-resolution N-body simulations. In particular, we focus on the topological properties of the "cosmic web", quantitatively characterized by the Minkowski Functionals, for models with quadratic non-linearities with different values of the usual non-Gaussianity parameter fNL. In the weakly non-linear regime, we find that analytic formulae derived from perturbation theory agree with the numerical results within a few percent of the amplitude of each MF when |fNL|<1000. In the non-linear regime, the detailed behavior of the MFs as functions of threshold density deviates more strongly from the analytical curves, while the overall amplitude of the primordial non-Gaussian effect remains comparable to the perturbative prediction. When smaller-scale information is included, the influence of primordial non-Gaussianity becomes increasingly significant statistically due to decreasing sample variance. We find that the effect of the primordial non-Gaussianity with |fNL|=50 is comparable to the sample variance of mass density fields with a volume of 0.125(Gpc/h)^3 when they are smoothed by Gaussian filter at a scale of 5Mpc/h. The detectability of this effect in actual galaxy surveys will strongly depend upon residual uncertainties in cosmological parameters and galaxy biasing.