Viscous ghost dark energy with a varying gravitational constant

Abstract

We study the ghost model of dark energy with a varying gravitational constant, G, in the presence of viscosity. In an isotropic and homogeneous Friedmann–Robertson–Walker (FRW) universe, the dissipative effects arise from the presence of bulk viscosity in cosmic fluids. We present the equation of state and the deceleration parameters for interacting viscous ghost dark energy (GDE) in a non-flat universe. We also obtain the dynamical equation governing the evolution of viscous GDE with a time-variable gravitational constant. Our study shows that in the case of a varying gravitational constant, the equation of state parameter of GDE can cross the phantom line (wD ⩽ − 1) in the late time where ΩD → 1, whereas at the present time it always satisfies wD > −1. We also find that at the present time, the deceleration parameter varies in the range −0.44 < q − ⩽0.38 as G varies between 0 < G′/G ⩽ 0.07.