Non-stationary de Sitter cosmological models

Abstract

In this note it is proposed a class of non-stationary de Sitter, rotating and non- rotating, solutions of Einstein’s field equations with a cosmological term of variable function Λ∗(u). It is found that the space-time of the rotating non-stationary de Sitter model is an algebraically special in the Petrov classification of gravitational field with a null vector, which is geodesic, shear free, expanding as well as non-zero twist. However, that of the non-rotating non-stationary model is conformally flat with non-empty space.