Energyreleasing black hole. Computer artwork of the energyreleasing black hole in galaxy MCG 6 3015. The energy around this black hole was measured by astronomers, using ESAs XMMNewton X ray observatory. It was found to be greater than expected. The extra energy is thought to be rotational energy extracted when the black holes spin is slowed by the twisting of magnetic field lines close to its border (event horizon). The gravity in this region is strong enough to twist the fabric of spacetime, resulting in the tightening of the magnetic field lines that slows the spin of the black hole. The energy released by the slowed black hole heats surrounding gas.