A marked correlation function for constraining modified gravity models

TL;DR

This paper proposes a density-marked correlation function as a new, practical statistical tool for testing modified gravity models using large scale structure survey data, focusing on density dependence.

Contribution

It introduces a density-marked correlation function as an easy-to-compute, density-dependent statistic for constraining modified gravity theories in cosmological surveys.

Findings

Demonstrates the concept using low order perturbation theory.

Suggests the statistic can discriminate between gravity models.

Encourages further exploration of this method in modified gravity research.

Abstract

Future large scale structure surveys will provide increasingly tight constraints on our cosmological model. These surveys will report results on the distance scale and growth rate of perturbations through measurements of Baryon Acoustic Oscillations and Redshift-Space Distortions. It is interesting to ask: what further analyses should become routine, so as to test as-yet-unknown models of cosmic acceleration? Models which aim to explain the accelerated expansion rate of the Universe by modifications to General Relativity often invoke screening mechanisms which can imprint a non-standard density dependence on their predictions. This suggests density-dependent clustering as a `generic' constraint. This paper argues that a density-marked correlation function provides a density-dependent statistic which is easy to compute and report and requires minimal additional infrastructure beyond what is routinely available to such survey analyses. We give one realization of this idea and study it using low order perturbation theory. We encourage groups developing modified gravity theories to see whether such statistics provide discriminatory power for their models.