Electrovac Universes with a Cosmological Constant

Abstract

We present the extension of the Einstein-Maxwell system called electrovac universes by introducing a cosmological constant $\Lambda$. In the absence of the $\Lambda$ term, the crucial equation in solving the Einstein-Maxwell system is the Laplace equation. The cosmological constant modifies this equation to become in a non-linear partial differential equation which takes the form $\Delta U=2\Lambda U^3$. We offer special solutions of this equation.