Dynamics of viable $f(R)$ dark energy models in the presence of Curvature-Matter interactions

TL;DR

This paper investigates how interactions between dark matter and curvature-driven dark energy in $f(R)$ gravity models influence cosmic evolution, revealing stable late-time acceleration and potential solutions to the cosmic coincidence problem.

Contribution

It introduces a specific matter-curvature interaction term into $f(R)$ models and analyzes its effects on the stability and evolution of the universe, extending prior dynamical system analyses.

Findings

Interaction modifies fixed points and their stability.

Stable late-time cosmic acceleration is achieved.

Interaction can address the cosmic coincidence problem.

Abstract

In this study, we analyze the dynamics of the interaction between dark matter and curvature-driven dark energy in viable $f(R)$ gravity models using the framework of dynamical system analysis. We incorporate this interaction by introducing a source term in their respective continuity equations, given by $Q = \frac{\kappa^2 \alpha}{3H}\tilde{\rho}_{\rm m}\rho_{\rm curv}$, and examine two $f(R)$ gravity models that comply with local gravity constraints and cosmological viability criteria. Our findings reveal subtle modifications to fixed points and their stability criteria when compared to the conventional dynamical analysis of $f(R)$ gravity models without matter-curvature interactions as proposed and examined in prior literature. We determine the parameter limits associated with the stability criteria of critical points of the dynamical system for both the models. Additionally, the introduction of interaction reveals variations in the dynamical aspects of cosmic evolution, contingent on the range of values for the relevant model parameters. These results are consistent with the observed features of cosmic evolution within specific limits of the $f(R)$ models parameters and the coupling parameter $\alpha$. We also examine the evolutionary dynamics of the universe in the interacting scenario through cosmological and cosmographic parameters. Our analysis demonstrates that the interacting scenario comprehensively accounts for all the observed phases of the universe's evolution and also results in a stable late-time cosmic acceleration. Additionally, we've studied how the coupling parameter affects evolutionary dynamics, particularly its impact on the matter-to-curvature energy density ratio. Our findings suggest that the chosen form of interaction can also address the cosmic coincidence problem.