The cosmology of $f(R, L_m)$ gravity: constraining the background and perturbed dynamics

TL;DR

This study investigates a specific modified gravity model, constraining its parameters using diverse cosmological datasets to assess its ability to explain the universe's accelerated expansion and structure formation.

Contribution

The paper introduces and tests a novel f(R, L_m) gravity model against observational data, providing a comprehensive statistical analysis of its cosmological viability.

Findings

The model fits observational data comparably to DM.

Constraints on model parameters nd eta are consistent with accelerated expansion.

The model can reproduce large-scale structure growth patterns.

Abstract

This paper delves into the late-time accelerated expansion of the universe and the evolution of cosmic structures within the context of a specific \( f(R, L_m) \) gravity model, formulated as \( f(R, L_m) = \lambda R + \beta L_m^\alpha + \eta \). To study the cosmological viability of the model, we employed the latest cosmic measurement datasets: i) 57 observational Hubble parameter data points (\texttt{OHD}); ii) 1048 distance moduli data points (\texttt{SNIa}); iii) a combined dataset (\texttt{OHD+SNIa}); and large scale structure datasets, including iv) 14 growth rate data points (\texttt{f}); and v) 30 redshift space distortion data points (\texttt{f}$\sigma_8$). These datasets facilitated the constraint of the \( f(R, L_m) \)-gravity model via MCMC simulations, followed by a comparative analysis with the \(\Lambda\)CDM model. A comprehensive statistical analysis has been conducted to evaluate the \( f(R, L_m) \)-gravity model's efficacy in explaining both the accelerated expansion of the universe and the growth of cosmic structures.