Cosmology in $f(R,L_m)$ gravity

TL;DR

This paper explores a modified gravity model, $f(R,L_m)$, to explain the universe's late-time acceleration, deriving exact solutions, fitting parameters with observational data, and analyzing stability and cosmic behavior.

Contribution

The study introduces a specific non-linear $f(R,L_m)$ model, derives exact cosmological solutions, and validates its consistency with observational data for late-time cosmic acceleration.

Findings

Model fits observational $H(z)$ and Pantheon datasets.

Deceleration parameter shows transition from deceleration to acceleration.

Model exhibits quintessence-like behavior and stability under perturbations.

Abstract

In this letter, we investigate the cosmic expansion scenario of the universe in the framework of $f(R,L_m)$ gravity theory. We consider a non-linear $f(R,L_m)$ model, specifically, $f(R,L_m)=\frac{R}{2}+L_m^n + \beta$, where $n$ and $\beta$ are free model parameters. Then we derive the motion equations for flat FLRW universe and obtain the exact solution of corresponding field equations. Then we estimate the best fit ranges of model parameters by using updated $H(z)$ datasets consisting of 57 points and the Pantheon datasets consisting of 1048 points. Further we investigate the physical behavior of density and the deceleration parameter. The evolution of deceleration parameter depicts a transition from deceleration to acceleration phases of the universe. Moreover, we analyze the stability of the solution of our cosmological model under the observational constraint by considering a linear perturbation. Lastlty, we investigate the behavior of Om diagnostic parameter and we observe that our model shows quintessence type behavior. We conclude that our $f(R,L_m)$ cosmological model agrees with the recent observational studies and can efficiently describe the late time cosmic acceleration.