LRS Bianchi Type I Models with Anisotropic Dark Energy and Constant Deceleration Parameter

TL;DR

This paper explores LRS Bianchi Type I cosmological models with anisotropic dark energy, deriving exact solutions that describe anisotropic universe expansion and potential implications for CMB anisotropy.

Contribution

It introduces new exact solutions for anisotropic dark energy models with a constant deceleration parameter, considering anisotropic equations of state and energy-momentum conservation.

Findings

Models exhibit dynamically anisotropic expansion.

Solutions allow tuning of isotropization and CMB anisotropy.

Dark energy anisotropy influences universe's expansion history.

Abstract

Locally rotationally symmetric (LRS) Bianchi Type I cosmological models are examined in the presence of dynamically anisotropic dark energy and perfect fluid. We assume that the dark energy (DE) is minimally interacting, has dynamical energy density, anisotropic equation of state parameter (EoS). The conservation of the energy-momentum tensor of the DE is assumed to consist of two separately additive conserved parts. A special law is assumed for the deviation from isotropic EoS, which is consistent with the assumption on the conservation of the energy-momentum tensor of the DE. Exact solutions of Einstein's field equations are obtained by assuming a special law of variation for the mean Hubble parameter, which yields a constant value of the deceleration parameter. Geometrical and kinematic properties of the models and the behaviour of the anisotropy of the dark energy has been carried out. The models give dynamically anisotropic expansion history for the universe that allows to fine tune the isotropization of the Bianchi metric, hence the CMB anisotropy.