The Effects of Primordial Non-Gaussianity on Giant-Arc Statistics: A Scale Dependent Example

TL;DR

This paper investigates how scale-dependent primordial non-Gaussianity, especially of the equilateral type, can significantly influence giant-arc statistics, potentially causing several-fold variations compared to Gaussian predictions.

Contribution

It introduces a model of scale-dependent non-Gaussianity with equilateral shape and quantifies its impact on giant-arc abundance, extending previous local non-Gaussianity studies.

Findings

Scale-dependent equilateral non-Gaussianity can increase giant-arc abundance by a factor of a few.

Compared to local non-Gaussianity, the equilateral shape yields a larger effect.

The effect can reach up to several times the Gaussian case within current constraints.

Abstract

In a recently published article, we quantified the impact of primordial non-Gaussianity on the probability of giant-arc formation. In that work, we focused on the local form of non-Gaussianity and found that it can have only a modest effect given the most recent constraints from Cosmic Microwave Background (CMB) measurements. Here, we present new calculations using a parameterization of scale-dependent non-Gaussianity in which the primordial bispectrum has the equilateral shape and the effective f_NL parameter depends on scale. We find that non-Gaussianity of this type can yield a larger effect on the giant-arc abundance compared to the local form due to both the scale dependence and the relatively weaker constraints on the equilateral shape from CMB measurements. In contrast to the maximum ~40% effect (within the latest CMB constraints) previously found for the local form, we find that the predicted giant-arc abundance for the scale-dependent equilateral form can differ by a factor of a few with respect to the Gaussian case.