Viscous Dark Energy and Phantom Field in An Anisotropic Universe

In this paper we have investigated the general form of viscous and non-viscous dark energy equation of state (EoS) parameter in the scope of anisotropic Bianchi type I space-time. We show that the presence of bulk viscosity causes transition of $\omega^{de}$ from quintessence to phantom but the phantom state is an unstable state (as expected) and EoS of DE tends to $-1$ at late time. Then we show this phantomic description of the viscous dark energy and reconstruct the potential of the phantom scalar field. It is found that bulk viscosity pushes the universe to a darker region. We have also shown that at late time $q\sim-\Omega^{de}$.Comment: 10 page

Accelerating dark energy models in bianchi Type-V space-time

Some new exact solutions of Einstein's field equations in a spatially homogeneous and anisotropic Bianchi type-V space-time with minimally interaction of perfect fluid and dark energy components have been obtained. To prevail the deterministic solution we choose the scale factor $a(t) = \sqrt{t^{n}e^{t}}$, which yields a time dependent deceleration parameter (DP), representing a model which generates a transition of the universe from the early decelerating phase to the recent accelerating phase. We find that for $n \geq 1$, the quintessence model is reproducible with present and expected future evolution of the universe. The other models (for $n < 1$), we observe the phantom scenario. The quintessence as well as phantom models approach to isotropy at late time. For different values of $n$, we can generate a class of physically viable DE models. The cosmic jerk parameter in our descended model is also found to be in good concordance with the recent data of astrophysical observations under appropriate condition. The physical and geometric properties of spatially homogeneous and anisotropic cosmological models are discussed.Comment: 12 pages, 6 figure

Bianchi type-III string cosmological models for stiff and anti-stiff fluid in general relativity

Bianchi type-III string cosmological models in the presence of stiff and anti-stiff fluids are studied. The scalar expansion is assumed to be proportional to the shear. In the present study, we consider two cases (i)p+ρ= 0 and (ii) p−ρ= 0, where ρ and p are the rest energy density and the pressure of the fluid, respectively. The physical behavior of these models is also discussed