The imprints of primordial non-gaussianities on large-scale structure: scale dependent bias and abundance of virialized objects

TL;DR

This paper investigates how primordial non-Gaussianities influence large-scale structure formation, especially the clustering and abundance of massive virialized objects, using analytic models and N-body simulations.

Contribution

It introduces a simple fitting function for the halo mass function and demonstrates the strong scale-dependent bias caused by non-Gaussianity, offering a new probe for early universe conditions.

Findings

Primordial non-Gaussianity significantly affects halo clustering.

Scale-dependent bias is enhanced for rare, massive objects.

Upcoming surveys could constrain |fNL| to about 10.

Abstract

We study the effect of primordial nongaussianity on large-scale structure, focusing upon the most massive virialized objects. Using analytic arguments and N-body simulations, we calculate the mass function and clustering of dark matter halos across a range of redshifts and levels of nongaussianity. We propose a simple fitting function for the mass function valid across the entire range of our simulations. We find pronounced effects of nongaussianity on the clustering of dark matter halos, leading to strongly scale-dependent bias. This suggests that the large-scale clustering of rare objects may provide a sensitive probe of primordial nongaussianity. We very roughly estimate that upcoming surveys can constrain nongaussianity at the level |fNL| <~ 10, competitive with forecasted constraints from the microwave background.