Verifying the consistency relation for the scale-dependent bias from local primordial non-Gaussianity

TL;DR

This paper tests the theoretical consistency of the scale-dependent bias from local primordial non-Gaussianity using simulations, finding good agreement with some models but notable deviations from the universal mass function predictions, especially at different mass scales.

Contribution

The study provides the first detailed comparison between measured halo bias in simulations and theoretical predictions for local non-Gaussianity, highlighting discrepancies in the universal mass function approach.

Findings

Bias measurements agree with response of mass function to primordial amplitude changes

Universal mass function prediction overestimates bias for high-mass halos by 10-15%

Bias behavior varies with halo mass and finder algorithm, especially at low masses

Abstract

We measure the large-scale bias of dark matter halos in simulations with non-Gaussian initial conditions of the local type, and compare this bias to the response of the mass function to a change in the primordial amplitude of fluctuations. The two are found to be consistent, as expected from physical arguments, for three halo-finder algorithms which use different Spherical Overdensity (SO) and Friends-of-Friends (FoF) methods. On the other hand, we find that the commonly used prediction for universal mass functions, that the scale-dependent bias is proportional to the first-order Gaussian Lagrangian bias, does not yield a good agreement with the measurements. For all halo finders, high-mass halos show a non-Gaussian bias suppressed by 10-15% relative to the universal mass function prediction. For SO halos, this deviation changes sign at low masses, where the non-Gaussian bias becomes larger than the universal prediction.