Cluster Density Profiles as a Test of Modified Gravity

TL;DR

This paper tests modified gravity theories using cluster-galaxy lensing data from SDSS, setting bounds on f(R) gravity parameters by comparing observations with simulations, and finds consistency with standard gravity.

Contribution

It introduces a new method to constrain f(R) gravity using cluster density profiles from weak lensing measurements, providing model-independent bounds.

Findings

Upper bound on f_R0<3.5x10^-3 at 95% confidence

Cluster profiles are consistent with standard gravity within uncertainties

Constraints are derived without relying on cluster abundance effects

Abstract

We present a new test of gravitational interactions at the r\sim(0.2-20)Mpc scale, around the virial radius of dark matter halos measured through cluster-galaxy lensing of maxBCG clusters from the Sloan Digital Sky Survey (SDSS). We employ predictions from self-consistent simulations of f(R) gravity to find an upper bound on the background field amplitude of f_R0<3.5x10^-3 at the 1D-marginalized 95% confidence level. As a model-independent assessment of the constraining power of cluster profiles measured through weak gravitational lensing, we also constrain the amplitude F_0 of a phenomenological modification based on the profile enhancement induced by f(R) gravity when not including effects from the increased cluster abundance in f(R). In both scenarios, dark-matter-only simulations of the concordance model corresponding to f_R0=0 and F_0=0 are consistent with the lensing measurements, i.e., at the 68% and 95% confidence level, respectively.