Matter bispectrum in cubic Galileon cosmologies

TL;DR

This paper calculates the dark matter bispectrum in cubic Galileon cosmologies using a semi-analytic method, revealing that deviations from ΛCDM at the bispectrum level are minimal despite large linear growth-rate differences.

Contribution

It provides the first semi-analytic calculation of the dark matter bispectrum in covariant cubic Galileon models, highlighting the small impact of linear growth deviations.

Findings

Deviations in the bispectrum are reduced to a few percent despite large linear growth-rate differences.

The semi-analytic approach effectively captures second-order perturbations in Galileon cosmologies.

Results suggest the bispectrum is less sensitive to Galileon modifications than linear growth rates.

Abstract

In this paper we obtain the bispectrum of dark matter density perturbations in the frame of covariant cubic Galileon theories. This result is obtained by means of a semi-analytic approach to second-order perturbations in Galileon cosmologies, assuming Gaussian initial conditions. In particular, we show that, even in the presence of large deviations of the linear growth-rate w.r.t. the {\Lambda}CDM one, at the bispectrum level such deviations are reduced to a few percent.