The interior structure of rotating black holes 3. Charged black holes
  This paper extends to the case of charged rotating black holes the
conformally stationary, axisymmetric, conformally separable solutions presented
for uncharged rotating black holes in a companion paper. In the present paper,
the collisionless fluid accreted by the black hole may be charged. The charge
of the black hole is determined self-consistently by the charge accretion rate.
As in the uncharged case, hyper-relativistc counter-streaming between ingoing
and outgoing streams drives inflation at (just above) the inner horizon,
followed by collapse. If both ingoing and outgoing streams are charged, then
conformal separability holds during early inflation, but fails as inflation
develops. If conformal separability is imposed throughout inflation and
collapse, then only one of the ingoing and outgoing streams can be charged: the
other must be neutral. Conformal separability prescribes a hierarchy of
boundary conditions on the ingoing and outgoing streams incident on the inner
horizon. The dominant radial boundary conditions require that the incident
ingoing and outgoing number densities be uniform with latitude, but the charge
per particle must vary with latitude such that the incident charge densities
vary in proportion to the radial electric field. The sub-dominant angular
boundary conditions require specific forms of the incident number- and
charge-weighted angular motions. If the streams fall freely from outside the
horizon, then the prescribed angular conditions can be achieved by the charged
stream, but not by the neutral stream. Thus, as in the case of an uncharged
black hole, the neutral stream must be considered to be delivered ad hoc to
just above the inner horizon.
