The James Webb Space Telescope has confirmed that a supermassive black hole is racing away from its host galaxy at approximately 2 million miles per hour — an extraordinary cosmic velocity that researchers attribute to a gravitational wave recoil kick following the merger of two massive black holes in the distant past.
The fleeing black hole, located roughly 7.5 billion light-years from Earth, trails a spectacular wake of newly formed stars stretching over 200,000 light-years — a distance larger than two Milky Way galaxies placed side by side. This glowing stellar trail made the runaway black hole detectable even as its core faded from view.
Gravitational Wave Recoil
When two supermassive black holes merge, the gravitational waves they emit are not always symmetric. If significantly more energy is radiated in one direction, the newly merged black hole receives a recoil "kick" in the opposite direction — a consequence of momentum conservation. In sufficiently energetic mergers, this kick can reach velocities capable of ejecting the black hole from its galaxy entirely.
This mechanism, long predicted by general relativity, has been extremely difficult to observe directly. Webb's infrared vision allowed researchers to trace the black hole's path through the surrounding medium, confirming that it is genuinely unbound from its original host galaxy and traveling into intergalactic space.