Revisiting the angular momentum growth of protostructures evolved from non-Gaussian initial conditions

TL;DR

This paper investigates how primordial non-Gaussianity influences the angular momentum growth of protostructures, finding that non-Gaussian effects are perturbatively tractable and contribute up to 20% on galactic scales.

Contribution

It extends previous models by analyzing additional bispectrum shapes and demonstrates that non-Gaussian effects can be described perturbatively across various inflationary scenarios.

Findings

Non-Gaussian contributions are up to 10-20% of linear growth.

Perturbation theory remains valid for the new bispectrum models.

Current bounds on $f_{NL}$ suggest modest non-Gaussian impact on protostructure spin.

Abstract

I adopt a formalism previously developed by Catelan and Theuns (CT) in order to estimate the impact of primordial non-Gaussianity on the quasi-linear spin growth of cold dark matter protostructures. A variety of bispectrum shapes are considered, spanning the currently most popular early Universe models for the occurrence of non-Gaussian density fluctuations. In their original work, CT considered several other shapes, and suggested that only for one of those does the impact of non-Gaussianity seem to be perturbatively tractable. For that model, and on galactic scales, the next-to-linear non-Gaussian contribution to the angular momentum variance has an upper limit of $\sim 10%$ with respect to the linear one. I find that all the new models considered in this work can also be seemingly described via perturbation theory. Considering current bounds on $f_\mathrm{NL}$ for inflationary non-Gaussianity leads to the quasi-linear contribution being $\sim 10-20%$ of the linear one. This result motivates the systematic study of higher-order non-Gaussian corrections, in order to attain a comprehensive picture of how structure gravitational dynamics descends from the physics of the primordial Universe.