On the galaxy 3-point correlation function in Modified Gravity

TL;DR

This paper develops a theoretical framework to analyze the three-point correlation function in modified gravity models, aiding future galaxy surveys in testing deviations from General Relativity using higher order statistics.

Contribution

It introduces a perturbation theory approach for the 3PCF in scale-dependent modified gravity models, specifically applying it to $f(R)$ and DGP models with screening mechanisms.

Findings

Theoretical characterization of 3PCF in modified gravity models.

Application to $f(R)$ and DGP models demonstrating deviations from GR.

Multipole decomposition enhances analysis and visualization.

Abstract

The next generation of galaxy surveys will provide highly accurate measurements of the large-scale structure of the Universe, allowing for more stringent tests of gravity on cosmological scales. Higher order statistics are a valuable tool to study the non-Gaussianities in the matter field and to break degeneracies between modified gravity and other physical or nuisance parameters. However, understanding from first principles the behaviour of these correlations is essential to characterise deviations from General Relativity (GR), and the purpose of this work. This work uses contemporary ideas of Standard Perturbation Theory on biased tracers to characterize the three point correlation function (3PCF) at tree level for Modified Gravity models with a scale-dependent gravitational strength, and applies the theory to two specific models ($f(R)$ and DGP) that are representative for Chameleon and Vainshtein screening mechanisms. Additionally, we use a multipole decomposition, which apart from speeding up the algorithm to extract the signal from data, also helps to visualize and characterize GR deviations.