10-02-2020, 10:35 PM
It doesn't matter if the mass-energy of a black hole is inside it or outside (for instance if it is emitted as radiation following a merger). Both forms of mass-energy create the same amount of gravity.
Indeed, if a pair of black holes lose energy by merging, that energy radiates away at or nearly at the speed of light (depending on what form the radiation takes), so relocates to another part of the universe. By radiating away mass-energy, a pair of black holes could cause the local mass-energy of a galaxy to become reduced.
Indeed, if a pair of black holes lose energy by merging, that energy radiates away at or nearly at the speed of light (depending on what form the radiation takes), so relocates to another part of the universe. By radiating away mass-energy, a pair of black holes could cause the local mass-energy of a galaxy to become reduced.