Viscous Bianchi Type I Universe with Stiff Matter and Decaying Vacuum Energy Density

Abstract EN

We examine homogeneous and anisotropic Bianchi type I cosmological model with viscous stiff matter and time-varying cosmological term Λ which scales with Hubble parameter H.

The resulting model approaches isotropy.

The cosmological term Λ relaxes to a genuine cosmological constant, and the model in the absence of bulk viscosity tends to a deSitter universe asymptotically.

Our scenario presents an initial epoch with decelerating expansion followed by late-time acceleration consistent with observations.

Bulk viscosity advances the accelerating phase in the model and prevents the matter density to vanish for large times.