Nonsingular spherical models with a variable cosmological term

Abstract

Exact solutions of the Einstein’s field equations describing a spheri- cally symmetric cosmological model without a big bang or any other kind of singularity recently obtained by Dadhich and Patel (2000) are revis- ited. The matter content of the model is a shear-free perfect fluid with isotropic pressure and a radial heat flux. Three different exact solutions are obtained for both perfect fluid and fluid with bulk viscosity. It turns out that the cosmological rerm Λ(t) is a decreasing function of time, which is consistent with recent observations of type Ia supernovae.