Dark energy and viscous cosmology with variable G and Λ in an anisotropic background

Abstract

The general Bianchi type I with dark energy in the form of standard and modified Chaplygin gas with variable G and Λ and bulk viscosity have been investigated. The de Sitter, power-law and general exponential solutions are assumed for the scale factor in each spatial direction and the corresponding cosmological models are reconstructed. Moreover, for the general exponential solutions, from which the de Sitter and power-law solutions may be obtained, we obtain models that reproduce the early universe, assumed as the inflation, and the late time accelerated expanding universe, that which yields a constant value for the deceleration parameter. We reconstruct bulk viscosity, ξ, gravitational parameter, G, cosmological term, Λ, density parameter, Ω, cosmological constant density parameter, ΩΛ, and deceleration parameter, q, for different equations of state. In the large time limit the model describes an accelerating universe wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.