A generalized local ansatz and its effect on halo bias

TL;DR

This paper investigates how a generalized local ansatz for primordial non-Gaussianity affects halo bias, revealing scale-dependent effects and stronger signals than predicted, which could help distinguish early universe models.

Contribution

It introduces a generalized local ansatz with scale-dependent bispectra and analyzes its impact on halo bias through simulations, providing new insights into observational signatures.

Findings

Non-Gaussian correction to halo bias depends on object scale.

Some bispectrum forms alter the bias scale dependence by fractional powers of k.

Simulations show a stronger observational signal than analytic predictions.

Abstract

Motivated by the properties of early universe scenarios that produce observationally large local non-Gaussianity, we perform N-body simulations with non-Gaussian initial conditions from a generalized local ansatz. The bispectra are schematically of the local shape, but with scale-dependent amplitude. We find that in such cases the size of the non-Gaussian correction to the bias of small and large mass objects depends on the amplitude of non-Gaussianity roughly on the scale of the object. In addition, some forms of the generalized bispectrum alter the scale dependence of the non-Gaussian term in the bias by a fractional power of k. These features may allow significant observational constraints on the particle physics origin of any observed local non-Gaussianity, distinguishing between scenarios where a single field or multiple fields contribute to the curvature fluctuations. While analytic predictions for the non-Gaussian bias agree qualitatively with the simulations, we find numerically a stronger observational signal than expected. This suggests that a more precise understanding of halo formation is needed to fully explain the consequences of primordial non-Gaussianity