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A runaway supermassive black hole flees cosmic owl galaxies, leaving a trail of stars. | Credit: Lee et al/Robert Lee (created with Canva)
Astronomers using the James Webb Space Telescope (JWST) have made a truly mind-blowing discovery: a black hole one million times the size of the Sun, rocketing through space at 22 million miles per hour (1,000 kilometers per second).
Not only does this make it the first confirmed runaway supermassive black hole, but the object is one of the fastest-moving bodies ever discovered, rocketing to its home, a pair of galaxies called “.Cosmic Owl,” at 3,000 times the speed of sound at sea level on Earth. If that’s not amazing enough, the black hole is pushing forward a literal galaxy-sized “bow-shock” of the object in front of it, while simultaneously dragging the 200,000 light-year-long tail and trigger gas behind it.
“It boggles the mind!” Peter van Dokkum, leader of the search team at Yale University, told Space.com. “The forces required to eject such a massive black hole from its home are enormous. And yet, such an escape was predicted!”
Supermassive black holesThose that can reach billions of times the mass of the Sun are usually found at the heart of their home galaxies, dominated by their massive gravity. The incredible speed of this supermassive black hole means it is about 230,000 light-years from its point of origin.
“This is the only black hole that has been found so far from its former home,” van Dokkum said. “That made it an excellent candidate [for a] Escaped supermassive black holes, but what was missing was confirmation. We really had a streak that was hard to explain any other way. With JWST, we have now confirmed that there is indeed a black hole at the tip of the streak, and that it is speeding away from its former host.”
Find out how to escape
It was a now-confirmed runaway supermassive black hole Van Dokkum and colleagues identified the first Using back in 2023 Hubble Space Telescope, who saw the cause of a gigantic body passing through space. Of course, like all black holes, this escape space is surrounded by a one-way light-trapping surface called the event horizon, making it difficult to detect.
“The black hole is, well, black – and it’s very difficult to detect when it’s passing through empty space. The reason we detect the object is because of the impact on its surroundings in the path of the black hole: we now know that it drives a shock wave in the moving gas, and it’s this shock wave, and this shock wave,” said the shock wave we saw behind the black hole. “With JWST, we detected a large displacement of gas at the top of the core, where the black hole is pushing against it. The shock signatures are crystal clear, and there’s no doubt about what’s going on here.” Gas is pushed out of the supermassive black hole at velocities of hundreds of thousands of miles per hour (hundreds of kilometers per second), a dynamic signature that the team observed with JWST.
Hubble image of runaway supermassive black hole now confirmed with wake probed by JWST | Credit: van Dokkum et al (2025) / arXiv
“The velocity of the displaced gas is directly related to the velocity of the black hole, and thus we determined the velocity of the black hole from the JWST data,” van Dokkum said. “It’s moving at about 1000 kilometers per second, faster than any object in the universe. It’s this high speed that enabled the black hole to escape the gravitational pull of its old home.”
How does a supermassive black hole ‘go rogue?’
Van Dokkum explained that two possible mechanisms could drive a supermassive black hole out of its own galaxy’s heart. Both scenarios begin when two galaxies collide and begin to merge, each bringing the universe into its own supermassive black hole. Both mechanisms are initiated when supermassive black holes approach the center of a newly formed galaxy.
“The first mechanism is two black holes colliding with each other, and that gravitational radiation [gravitational waves] That gives a powerful kick to the newly formed black hole released in the merger. That kick can provide an acceleration of 1,000 km/s, enough to eject a black hole,” van Dokkum said. “The second is a three-body interaction. That happens when one of the two galaxies was a pair Binary black holes At its center. When the third black hole enters the binary system, it becomes unstable, and one of the three black holes will be ejected from the system.”
The team believes this is the first scenario to account for a runaway supermassive black hole in this instance. This would lead to the galaxy lacking a supermassive black hole at its center, which van Dokkum said is unlikely to affect the galaxy much. However, this runaway supermassive black hole could have a massive impact on any galaxy it encounters as it rockets through space.
“An encounter with another galaxy would be very spectacular, mainly because of the massive, galaxy-sized shock wave that precedes the black hole,” van Dokkum continued. “When this shock wave encounters the dense gas of another galaxy, it compresses and shocks that gas, and many new stars are likely to form. It’s going to be quite a show!”
Fortunately, the two-ring galaxies that comprise the Cosmic Owl are located about 9 billion light-years away, meaning that even if this runaway cosmic titan were headed our way, we wouldn’t have to worry about it reaching us.
Mergers between galaxies are common, occurring several times during the lifetime of a single galaxy. This means that ejected supermassive black holes may also be common, although the population numbers vary depending on how these collisions are modeled.
“Mergers happen often in the life of a galaxy; every galaxy the size and mass of the Milky Way has experienced several in its lifetime. So black hole binaries must form regularly. We don’t know how quickly these binaries merge, if at all, and how often the resulting kick ejects the black hole,” van Dokkum said. “My idea is empirical: now that we know how to look for them, we can find other examples – and then we can answer the question directly from the data, by counting the number of escapes. The big thing is that black hole escapes survived purely in the realm of theory.” Although supermassive black holes have been predicted by theory, these discoveries long ago ‘discovered’ the situation. Unexpected twists.
“Everything about this research surprised me! I didn’t expect to see something like this, and the confirmation with JWST was incredible,” said van Dokkum. “We don’t even understand how much effect these ejected black holes have on the gas that they pass through. Later, many new stars are formed from shocked gas, about 100 million times the mass of the Sun. This mode of star formation was previously unknown, and it leads to the path of stars, visible in the shape of galaxies.
The Yale University researchers said the obvious next step for the team would be to look for more examples of runaway black holes.
“You need space-based imaging to see them: the wake stood out to us because it’s such a thin streak, and on ground-based images, it would be blurred beyond recognition,” van Dokkum explained. “Fortunately, wide field Hubble-quality imaging is just around the corner, thanks to the Roman Space Telescope, and, a little more obscurely, Euclid. Using machine learning algorithms to find thin lines in the Roman data would be a great project!”
The team’s research has been submitted to the Astrophysical Journal Letters and is currently available as a pre-peer-reviewed paper. arXiv.
