On the current status of Modified Gravity

TL;DR

This paper assesses the current observational constraints on the Hu & Sawicki modified gravity model, analyzing its effects on cosmological observables and providing bounds based on recent data, with prospects for future improvements.

Contribution

It offers a comprehensive analysis of the cosmological viability of the Hu & Sawicki modified gravity model using latest data and forecasts future survey impacts.

Findings

Strongest bound on model parameter: |f_{R0}| < 3.7 x 10^{-6} at 95% CL

Current data constrains the relationship between σ_8 and Ω_m

Future surveys could tighten these constraints significantly

Abstract

We revisit the cosmological viability of the Hu $\&$ Sawicki modified gravity scenario. The impact of such a modification on the different cosmological observables, including gravitational waves, is carefully described. The most recent cosmological data, as well as constraints on the relationship between the clustering parameter $\sigma_8$ and the current matter mass-energy density $\Omega_m$ from cluster number counts and weak lensing tomography, are considered in our numerical calculations. The strongest bound we find is $|f_{R0}| < 3.7 \times 10^{-6}$ at $95\%$~CL. Forthcoming cluster surveys covering 10,000 deg$^2$ in the sky, with galaxy surface densities of $\mathcal{O}(10)$~arcmin$^{-2}$ could improve the precision in the $\sigma_8$-$\Omega_m$ relationship, tightening the above constraint.