Electrostatic equilibrium of two spherical charged masses in general relativity

Abstract

Approximate solutions representing the gravitational - electrostatic balance of two arbitrary point sources in general relativity have led to contradictory arguments in the literature with respect to the condition of balance. Up to the present time, the only known exact solutions which can be interpreted as the nonlinear superposition of two spherically symmetric (Reissner - Nordström) bodies without an intervening strut have been for critically charged masses, . In the present paper, an exact electrostatic solution of the Einstein - Maxwell equations representing the exterior field of two arbitrary charged Reissner - Nordström bodies in equilibrium is studied. The invariant physical charge for each source is found by direct integration of Maxwell's equations. The physical mass for each source is defined invariantly in a manner similar to the way in which the charge was found. It is shown through numerical methods that balance without tension or strut can occur for non-critically charged bodies. It is demonstrated that other authors have not identified the correct physical parameters for the mass and charge of the sources. Further properties of the solution, including the multipole structure and comparison with other parametrizations, are examined.