Bijan Saha

Anisotropic Cosmological Models with a Perfect Fluid and a Λ Term

We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy given by a cosmological constant. The perfect fluid is chosen to be the one obeying either the usual equation of state, i.e., p = ζ, with ζ ∊ [0, 1] or a van der Waals equation of state. Role of the Λ term in the evolution of the BI Universe has been studied.

Spinor field in Bianchi type I universe: Regular solutions

Self-consistent solutions to the nonlinear spinor field equations in general relativity are studied for the case of Bianchi type-I (BI) space-time. It is shown that, for some special type of nonlinearity the model provides a regular solution, but this singularity-free solution is attained at the cost of breaking the dominant energy condition in the Hawking-Penrose theorem. It is also shown that the introduction of a

Bianchi type I cosmology with scalar and spinor fields

\ensuremath{\Lambda}

BIANCHI TYPE I UNIVERSE WITH VISCOUS FLUID

term in the Lagrangian generates oscillations of the BI model, which is not the case in the absence of a

An Interacting Two-Fluid Scenario for Dark Energy in an FRW Universe

\ensuremath{\Lambda}

Anisotropic Cosmological Models with Perfect Fluid and Dark Energy Reexamined

term. Moreover, for the linear spinor field, the

LRS Bianchi-I anisotropic cosmological model with dominance of dark energy

\ensuremath{\Lambda}

Two-fluid scenario for dark energy models in an FRW universe-revisited

term provides oscillatory solutions, which are regular everywhere, without violating the dominant energy condition.

Nonlinear spinor field in cosmology

We consider a system of interacting spinor and scalar fields in a gravitational field given by a Bianchi type-I cosmological model filled with perfect fluid. The interacting term in the Lagrangian is chosen in the form of derivative coupling, i.e.,

Bianchi type I universe with viscous fluid and a ^ term : A qualitative analysis

{\cal L}_{\rm int} = \frac{\lambda}{2} \vf_{,\alpha}\vf^{,\alpha} F