CLASH-VLT: constraints on $f(R)$ gravity models with galaxy clusters using lensing and kinematic analyses

TL;DR

This study uses galaxy cluster data from CLASH and VLT to constrain $f(R)$ gravity models, focusing on the fifth force interaction range, and finds limits consistent with or slightly tensioned from $ ext{Lambda}$CDM predictions.

Contribution

First combined kinematic and lensing analysis of galaxy clusters to constrain $f(R)$ gravity parameters, providing new limits on the fifth force interaction range.

Findings

MACSJ 1206: upper limit $ ext{lambda} extless= 1.61$ Mpc

RXJ 2248: lower limit $ ext{lambda} extgreater= 0.14$ Mpc

Possible tension with $ ext{Lambda}$CDM in lensing and kinematic data comparison.

Abstract

We perform a maximum likelihood kinematic analysis of the two dynamically relaxed galaxy clusters MACS J1206.2-0847 at $z=0.44$ and RXC J2248.7-4431 at $z=0.35$ to determine the total mass profile in modified gravity models, using a modified version of the MAMPOSSt code of Mamon, Biviano and Bou\'e. Our work is based on the kinematic and lensing mass profiles derived using the data from the Cluster Lensing And Supernova survey with Hubble (hereafter CLASH) and the spectroscopic follow-up with the Very Large Telescope (hereafter CLASH-VLT). We assume a spherical Navarro-Frenk-White (NFW hereafter) profile in order to obtain a constraint on the fifth force interaction range $\lambda$ for models in which the dependence of this parameter on the enviroment is negligible at the scale considered (i.e. $\lambda=const$) and fixing the fifth force strength to the value predicted in $f(R)$ gravity. We then use information from lensing analysis to put a prior on the other NFW free parameters. In the case of MACSJ 1206 the joint kinematic+lensing analysis leads to an upper limit on the effective interaction range $\lambda\le1.61\,\mbox{Mpc}$ at $\Delta\chi^{2}=2.71$ on the marginalized distribution. For RXJ 2248 instead a possible tension with the $\Lambda$CDM model appears when adding lensing information, with a lower limit $\lambda\ge0.14\,\mbox{Mpc}$ at $\Delta\chi^{2}=2.71$. This is consequence of the slight difference between the lensing and kinematic data, appearing in GR for this cluster, that could be explained in terms of modifications of gravity. We discuss the impact of systematics and the limits of our analysis as well as future improvements of the results obtained.[...]