Late-time cosmology in $f(Q, L_m)$ gravity: Analytical solutions and observational fits

TL;DR

This paper explores late-time cosmic expansion within $f(Q, L_m)$ gravity, deriving analytical solutions, constraining model parameters with observational data, and analyzing the universe's acceleration transition.

Contribution

It introduces a linear $f(Q, L_m)$ model, constrains its parameters using multiple datasets, and studies the universe's expansion and transition redshift within this framework.

Findings

Model parameters constrained with high precision.

Energy density remains positive and approaches zero in the future.

Transition redshifts indicate a shift from deceleration to acceleration.

Abstract

In this study, we examined the late-time cosmic expansion of the universe within the framework of $f(Q, L_m)$ gravity, where $Q$ denotes the non-metricity and $L_{m}$ represents the matter Lagrangian. We analyzed a linear $f(Q, L_m)$ model of the form $f(Q, L_m) = -\alpha Q + 2 L_{m} + \beta$. Using MCMC methods, we constrained the model parameters $H_0$, $\alpha$, and $\beta$ with various datasets, including $H(z)$, Pantheon+SH0ES, and BAO data. For the $H(z)$ dataset, we found $H_0 = 67.90 \pm 0.66$, $\alpha = 0.1072_{-0.0069}^{+0.0054}$, and $\beta = -1988.2 \pm 1.0$. For the Pantheon+SH0ES dataset, $H_0 = 70.05 \pm 0.68$, $\alpha = 0.0916_{-0.0033}^{+0.0028}$, and $\beta = -1988.3 \pm 1.0$. For the BAO dataset, $H_0 = 68.1 \pm 1.0$, $\alpha = 0.1029_{-0.0052}^{+0.0041}$, and $\beta = -1988.24 \pm 0.99$. Moreover, the energy density remains positive and approaches zero in the distant future, and the deceleration parameter indicates a transition from deceleration to acceleration, with transition redshifts of $z_t = 0.60$, $z_t = 0.78$, and $z_t = 0.66$ for the respective datasets. These findings align with previous observational studies and contribute to our understanding of the universe's expansion dynamics.