One of the subjects which is subject to controversy these days, is to what extent a real black hole may (not) have any features.
Certain principles in Physics are thought to be stronger, than the existence of black holes. One of those is ‘conservation of momentum’, and another is ‘conservation of charge’. Conservation of momentum already implies, that a black hole is capable of having spin, because the environment could act on it over time, exerting torque. Conservation of charge is often overlooked.
If for some reason, a black hole was to end up capturing electrons in disproportion to how many protons it captures, then what should also happen is that it should build up negative charge. This idea might cause some laughter, but the result of such a scenario would nevertheless follow.
What can be even harder to foresee, is what would happen if the black hole both had considerable charge, as well as spin. According to general principles in Physics, this would imply a ‘convection current’, and then such a black hole should also have a magnetic field.
Only, until recently it was thought that both the amount of charge-imbalance in captured matter, as well as the rate of spin, should be quite small. It was only a recent estimate I heard of, that the rate of spin was in some cases 1/3 the speed of light !!
Also, it has been proposed that there is an ‘energy jet’ which black holes emit. This energy jet might form from the accretion disk, because a strong magnetic field will generally tend to do two things to a plasma: It will compress a plasma, and it will generally tend to force its path of motion, to follow the lines of force, of the magnetic field. The latter is true, because the individual ionized particle do not travel in straight lines, instead traveling in helical paths, that are curved by an applied magnetic field. The helical paths which charged particles follow, will tend to rotate around the axis of the field, but will extend along its axis.
Well nobody has yet answered, whether the ‘energy jet’ from a black hole, initially consists mostly of protons, or of electrons and protons in a perfectly balanced way… If it was to consist mostly of the more massive protons, then the black hole and its surrounding phenomena should also become increasingly negatively charged… I do not actually visualize, the energy jet from a black hole consisting greatly of electrons…