Generalized local ansatz for scale-dependent primordial non-Gaussianities and future galaxy surveys

TL;DR

This paper develops a generalized framework for scale-dependent local primordial non-Gaussianities, enabling better comparison with observations and forecasting constraints from future galaxy surveys.

Contribution

It introduces a generalized formalism for local-type non-Gaussianities that includes scale dependence, applicable to a wide range of models, and provides forecasting tools for upcoming surveys.

Findings

Derived generalized bispectrum and trispectrum expressions with scale dependence.

Formulated large-scale power spectrum and bispectrum for biased objects.

Projected constraints on non-Gaussianity parameters for future galaxy surveys.

Abstract

We revisit a possible scale-dependence of local-type primordial non-Gaussianities induced by super-horizon evolution of scalar field perturbations. We develop the formulation based on $\delta N$ formalism and derive the generalized form of the local-type bispectrum and also trispectrum which allows us to implement the scale-dependence and suitably compare model prediction with observational data. We propose simple but phenomenologically meaningful expressions, which encompass the information of a wide range of physically motivated models. We also formulate large-scale power spectrum and bispectrum of biased objects in the presence of the scale-dependent primordial non-Gaussianities. We perform the Fisher analysis for future galaxy surveys and give the projected constraints on the parameters of the generalized local-form of primordial non-Gaussianities.