Generalized ghost dark energy in Brans-Dicke theory

TL;DR

This paper explores a generalized ghost dark energy model within Brans-Dicke cosmology, analyzing its evolution, equation of state, and potential to cross the phantom divide, offering insights into dark energy dynamics.

Contribution

It extends the ghost dark energy model to Brans-Dicke theory and investigates its cosmological implications and behavior.

Findings

The equation of state can cross the phantom line.

The model's evolution is governed by a specific differential equation.

Cosmological parameters are derived and analyzed.

Abstract

It was argued that the vacuum energy of the Veneziano ghost field of QCD, in a time-dependent background, can be written in the general form, $H + O(H^2)$, where $H$ is the Hubble parameter. Based on this, a phenomenological dark energy model whose energy density is of the form $\rho=\alpha H+\beta H^{2}$ was recently proposed to explain the dark energy dominated universe. In this paper, we investigate this generalized ghost dark energy model in the setup of Brans-Dicke cosmology. We study the cosmological implications of this model. In particular, we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of this dark energy model. It is shown that the equation of state parameter of the generalized ghost dark energy can cross the phantom line ($w_D=-1$) in some range of the parameters spaces.