Effects of anisotropy on interacting ghost dark energy in Brans-Dicke theories

TL;DR

This study investigates how anisotropy influences the behavior and stability of interacting ghost dark energy within Brans-Dicke cosmology, comparing growth of structures to standard models using observational data.

Contribution

It introduces a detailed analysis of anisotropic effects on ghost dark energy in Brans-Dicke theory, including stability and observational constraints, which is novel.

Findings

Anisotropy increases the growth rate of perturbations in ghost DE models.

The growth factor in ghost DE models surpasses that of ΛCDM in anisotropic universes.

The model's stability depends on the squared sound speed sign.

Abstract

By interacting ghost dark energy (ghost DE) in the framework of Brans-Dicke theory, a spatially homogeneous and anisotropic Bianchi type I Universe has been studied. For this purpose, we use the squared sound speed $c_s^2$ whose sign determines the stability of the model. As well as we probe observational constraints on the ghost dark energy models as the unification of dark matter and dark energy by using the latest observational data. In order to do so, we focus on observational determinations of the Hubble expansion rate (namely, the expansion history) $H(z)$. After that we evaluate the evolution of the growth of perturbations in the linear regime for both ghost DE and Brans-Dicke theory and compare the results with standard FRW and $\Lambda$CDM models. We display the effects of the anisotropy on the evolutionary behavior the ghost DE models where the growth rate is higher in this models. Eventually the growth factor for the $\Lambda$CDM Universe will always fall behind the ghost DE models in an anisotropic Universe