Can $f(Q)$ gravity challenge $\Lambda$CDM?

TL;DR

This paper investigates $f(Q)$ gravity models that mimic $ ext{Lambda}$CDM expansion but alter linear perturbations, using diverse cosmological data to constrain parameters and find some statistical preference over $ ext{Lambda}$CDM.

Contribution

It provides observational constraints on $f(Q)$ gravity models that replicate $ ext{Lambda}$CDM expansion history while modifying perturbation evolution, and finds potential statistical preference over $ ext{Lambda}$CDM.

Findings

Model fits low-$ ext{l}$ CMB better than $ ext{Lambda}$CDM.

Data constrains modifications to gravity at linear perturbation level.

Model is statistically preferred by combined cosmological data.

Abstract

We study observational constraints on the non-metricity $f(Q)$-gravity which reproduces an exact $\Lambda$CDM background expansion history while modifying the evolution of linear perturbations. To this purpose we use Cosmic Microwave Background (CMB) radiation, baryonic acoustic oscillations (BAO), redshift-space distortions (RSD), supernovae type Ia (SNIa), galaxy clustering (GC) and weak gravitational lensing (WL) measurements. We set stringent constraints on the parameter of the model controlling the modifications to the gravitational interaction at linear perturbation level. We find the model to be statistically preferred by data over the $\Lambda$CDM according to the $\chi^2$ and deviance information criterion statistics for the combination with CMB, BAO, RSD and SNIa. This is mostly associated to a better fit to the low-$\ell$ tail of CMB temperature anisotropies.