The inhomogeneous equation of state and the speed of convergence to a small cosmological constant

The inhomogeneous equation of state and the road towards the solution of the cosmological constant problem

We present a cosmological model containing a cosmological constant Λ and a component with an inhomogeneous equation of state. We study the form of the inhomogeneous equation of state for which the model exhibits the relaxation of the cosmological constant, i.e. it asymptotically tends to the de Sitter regime characterized by a small positive effective cosmological constant. The effect of the re...

A Quasilinear Parabolic Equation With Inhomogeneous Density and Absorption

Spacetimes admitting quasi-conformal curvature tensor

‎The object of the present paper is to study spacetimes admitting‎ ‎quasi-conformal curvature tensor‎. ‎At first we prove that a quasi-conformally flat spacetime is Einstein‎ ‎and hence it is of constant curvature and the energy momentum tensor of such a spacetime satisfying‎ ‎Einstein's field equation with cosmological constant is covariant constant‎. ‎Next‎, ‎we prove that if the perfect flui...

جوابهای کیهانشناسی معادلات برانس- دیکی با ثابت کیهانشناسی

  In this paper, the analytical solutions of Brans-Dicke (B-D) equations with cosmological constant are presented, in which the equation of state of the universe is P=mÙ° ρ , under the assumption φRn=c between the B-D field and the scale factor of the universe. The flat (K=0) Robertson- Walker metric has been considered for the metric of the universe. These solutions are rich in the sense that ...

A Higher Order B-Splines 1-D Finite Element Analysis of Lossy Dispersive Inhomogeneous Planar Layers

In this paper we propose an accurate and fast numerical method to obtain scattering fields from lossy dispersive inhomogeneous planar layers for both TE and TM polarizations. A new method is introduced to analyze lossy Inhomogeneous Planar Layers. In this method by applying spline based Galerkin’s method of moment to scalar wave equation and imposing boundary conditions we obtain reflection and...