Interacting Ghost Dark Energy with Sign-Changeable Coupling in Brans-Dicke Cosmology

TL;DR

This paper explores a ghost dark energy model within Brans-Dicke cosmology, examining its evolution, phase transitions, and thermodynamic consistency, with a focus on sign-changeable interactions and scalar field effects.

Contribution

It introduces a novel interacting ghost dark energy model with a sign-changeable coupling in Brans-Dicke cosmology, analyzing its cosmological and thermodynamic behavior.

Findings

The equation of state shows quintessence-like behavior, with phantom-like possibilities.

The universe transitions from deceleration to acceleration and may decelerate again in the future.

The generalized second law of thermodynamics holds in the model.

Abstract

In this study, we analyze the ghost dark energy model in Brans-Dicke cosmology in the framework of a flat Friedmann-Lemaitre-Robertson-Walker universe. We consider an interaction between ghost dark energy and dark matter with a sign-changeable interaction term. To discuss the cosmological implications of the model, we consider a well-motivated logarithmic form of the Brans-Dicke scalar field. By deriving the cosmological evolution equations, we obtain the cosmological parameters such as the equation of state and deceleration parameters. We analyze the behavior of the cosmological parameters by plotting their graphs against the redshift parameter ($z$). We observe that the equation of state parameter shows quintessence-like behaviour during present and future epochs; however, phantom-like behavior is also possible for suitable values of the model parameters. Analysis of the deceleration parameter shows a smooth recent phase transition of the universe (deceleration to acceleration). An interesting result we observe is the decelerated expansion of the universe in the far future, i.e, the universe experiences another phase transition in the future. The physical significance of the well-known cosmological plane ($w_D-w_D'$ plane) is discussed in our model. We observe that the trajectories start in the freezing region with the same initial behavior, deviate from each other during the evolution and ends in the thawing region. Finally, we perform a detailed thermodynamic analysis and demonstrate that the generalized second law of thermodynamics is satisfied within the present interacting ghost dark energy model.