Superposition of fields of two rotating charged masses in General Relativity and existence of equilibrium configurations

Understand

It is known that two Reissner-Nordstrom black holes or two overextreme Reissner-Nordstrom sources cannot be in physical equilibrium.

• In the static case such equilibrium is possible only if one of the sources is a black hole and another one is a naked singularity.
• We define the notion of physical equilibrium in general (stationary) case when both components of a binary system are rotating and show that such system containing a Kerr-Newman black hole and a Kerr-Newman naked singularity also can stay in physical equilibrium.
• The similar question about the system of two charged rotating black holes or two rotating overextreme charged sources still remains open.