Multi-scale perturbation theory II: Solutions and leading-order bispectrum in the ΛcDM universe

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Date

2021

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Journal ISSN

Volume Title

Publisher

IOP Publishing

Abstract

Two-parameter perturbation theory (2PPT) is a framework designed to include the relativistic gravitational effects of small-scale nonlinear structures on the large-scale properties of the Universe. In this paper we use the 2PPT framework to calculate and study the bispectrum of matter in a spatially-flat ΛCDM cosmology. This is achieved by deploying Newtonian perturbation theory to model the gravitational fields of quasi-nonlinear structures, and then subsequently using them as source terms for the large-scale cosmological perturbations. We find that our approach reproduces some of the expected relativistic effects from secondorder cosmological perturbation theory, but not all. This work therefore provides a first step in deploying a formalism that can simultaneously model the weak gravitational fields of both linear and nonlinear structures in a realistic model of the Universe

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Keywords

cosmological perturbation theory, gravity, non-gaussianity, power spectrum

Citation

Gallagher, Christopher & Clifton, Timothy & Clarkson, Chris. (2021). Multi-scale perturbation theory II: Solutions and leading-order bispectrum in the ΛCDM universe. Journal of Cosmology and Astroparticle Physics. 2021. 048. 10.1088/1475-7516/2021/08/048.