On the current status of Modified Gravity

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 $σ_8$ and the current matter mass-energy density $Ω_m$ 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 $σ_8$-$Ω_m$ relationship, tightening the above constraint.

11 pages, 6 figures and 2 Tables. Final published version in the PRD journal