Bianchi type-II inflationary models with stiff matter and decaying cosmological term

Abstract

We deal with Einstein's field equations with a time-decaying cosmological term of the forms (i) = β(α̈/α) + α/α 2 and (ii)= α/α2, where α is the average scale factor of the universe, α and β are constants for a spatially homogeneous and anisotropic LRS Bianchi type-II spacetime. Exact solutions of the field equations for stiff matter are obtained by applying a special law of variation for the Hubble parameter. Anisotropic cosmological models are presented with a constant negative deceleration parameter which corresponds to the accelerated phase of the present universe. The cosmological constant. is obtained as a decreasing function of time that is approaching a small positive value at the present epoch, which is corroborated by the consequences from recent supernovae Ia observations. The physical and kinematical behaviors of the models are also discussed.© 2014 Chinese Physical Society and IOP Publishing Ltd.