Viability of general relativity and modified gravity cosmologies using high-redshift cosmic probes
Fernanda Oliveira, Bruno Ribeiro, Wiliam S. Hipólito-Ricaldi, Felipe Avila, Armando Bernui
TL;DR
This study tests General Relativity-based and Modified Gravity cosmologies against high-redshift probes by jointly fitting background observables $H(z)$ and $D_L(z)$ with growth data $[f\sigma_8](z)$ using MCMC, while also performing non-parametric Gaussian Process reconstructions of the same quantities. The analysis reveals that background observables alone poorly discriminate among models, but incorporating growth data exposes deviations consistent with small departures from GR. The $F(Q)$ model, along with non-flat $\Lambda$CDM and $\omega$CDM, are competitive with $\Lambda$CDM in terms of the Akaike Information Criterion, whereas $F(R)$ models are strongly disfavored; however, the Bayesian Information Criterion still favors $\Lambda$CDM overall. Overall, the work demonstrates that combining parametric and non-parametric approaches with growth data provides a robust framework to evaluate the observational viability of alternative gravity theories for current and future surveys, highlighting $F(Q)$ as a particularly promising candidate outside standard GR.
Abstract
Several models based on General Relativity and Modified Gravity aim to reproduce the observed universe with precision comparable to the flat-$Λ$CDM cosmological model. In this study, we investigate the consistency of some of these models with current high-redshift cosmic data, assessing their ability to simultaneously describe both the background expansion and matter clustering, using measurements of the Hubble parameter $H(z)$, the luminosity distance $D_L(z)$, and the growth rate of structures $[fσ_8](z)$ through parametric and non-parametric methods. Our results indicate that background observables alone offer limited capacity to distinguish between models, while the inclusion of growth of structures data proves useful in revealing deviations, even if small. An $F(Q)$ model, the non-flat $Λ$CDM and the $ω$CDM emerge as alternatives well supported by data, closely matching the growth data and showing performance comparable to $Λ$CDM, as revealed by the Akaike Information Criterion. In contrast, $F(R)$ models are strongly disfavored compared to $Λ$CDM and $F(Q)$. However, according to the Bayesian Information Criterion, $Λ$CDM remains the preferred model among the models analysed. These analyses illustrate the usefulness of both parametric and non-parametric approaches to explore the observational viability of alternative cosmological models.