Why do black holes have a charge

Black holes easier than expected

Black holes can be characterized solely by their mass, their rotation and their electrical charge. So far, however, this has only been proven under idealized conditions. Norman G├╝rlebeck from the Center for Applied Space Technology and Microgravity in Bremen was able to show the astonishing simplicity of these celestial bodies in complex astrophysical situations, as he reports in the journal "Physical Review Letters".

Black holes represent the final stage in the development of enormously massive stars. Neither matter nor light can escape such an object. So far, it has only been possible to show under certain assumptions that a black hole can be fully described from the outside using just three parameters: It was assumed that black holes exist alone in the universe and that there are no other stars. But in space black holes sometimes have a companion - another black hole or a star - or are surrounded by a disk of matter. All of this causes the black hole to be deformed by an additional gravitational field. This phenomenon is similar to the tides on earth, which are mainly caused by the gravitational pull of the moon.

Several international research teams are investigating the question of whether such specimens can only be described by three parameters. G├╝rlebeck was now able to show through theoretical considerations that, despite the deformation of the black holes, no further parameters are required for characterization. For gravitational physicists, the new knowledge is an important basis for interpreting gravitational waves. These waves in space-time, which have not yet been directly detected, arise primarily in double systems.