Constraints on $f(R)$ gravity from tSZE-selected SPT galaxy clusters and weak lensing mass calibration from DES and HST

TL;DR

This study constrains $f(R)$ gravity using galaxy cluster counts from tSZE detection, weak lensing mass calibration, and Planck CMB data, setting the tightest limits to date on deviations from general relativity.

Contribution

It provides the first tight cosmological constraints on $f(R)$ gravity using a large cluster sample with weak lensing calibration and Planck data.

Findings

Upper limit on $|f_{R0}|$ is less than 10^{-5.32} at 95% credible level.

$f(R)$ deviations causing >20% increase in cluster counts are ruled out.

Cluster counts combined with CMB data yield the strongest constraints on $f(R)$ gravity.

Abstract

We present constraints on the $f(R)$ gravity model using a sample of 1,005 galaxy clusters in the redshift range $0.25 - 1.78$ that have been selected through the thermal Sunyaev-Zel'dovich effect (tSZE) from South Pole Telescope (SPT) data and subjected to optical and near-infrared confirmation with the Multi-component Matched Filter (MCMF) algorithm. We employ weak gravitational lensing mass calibration from the Dark Energy Survey (DES) Year 3 data for 688 clusters at $z < 0.95$ and from the Hubble Space Telescope (HST) for 39 clusters with $0.6 < z < 1.7$. Our cluster sample is a powerful probe of $f(R)$ gravity, because this model predicts a scale-dependent enhancement in the growth of structure, which impacts the halo mass function (HMF) at cluster mass scales. To account for these modified gravity effects on the HMF, our analysis employs a semi-analytical approach calibrated with numerical simulations. Combining calibrated cluster counts with primary cosmic microwave background (CMB) temperature and polarization anisotropy measurements from the Planck2018 release, we derive robust constraints on the $f(R)$ parameter $f_{R0}$. Our results, $\log_{10} |f_{R0}| < -5.32$ at the 95 % credible level, are the tightest current constraints on $f(R)$ gravity from cosmological scales. This upper limit rules out $f(R)$-like deviations from general relativity that result in more than a $\sim$20 % enhancement of the cluster population on mass scales $M_\mathrm{200c}>3\times10^{14}M_\odot$.