The imprints of primordial non-gaussianities on large-scale structure: scale dependent bias and abundance of virialized objects
Neal Dalal, Olivier Doré, Dragan Huterer, Alexander Shirokov
TL;DR
The paper investigates how primordial non-Gaussianity (NG) leaves imprints on the abundance and clustering of the most massive dark matter halos. It combines analytic estimates under a local $f_{\rm NL}$ model with N-body simulations to quantify changes in the halo mass function and in halo bias, and to calibrate a practical fitting formula for the mass function. A key result is that NG generates a pronounced scale-dependent bias on large scales, enabling forecasts that upcoming surveys could constrain $|f_{\rm NL}|\lesssim 10$, competitive with CMB bounds. Together, the work provides a framework for using cluster statistics and large-scale halo clustering as sensitive probes of primordial NG and inflationary physics.
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.