A team of astronomers claims that its research confirms the discovery of the first galactic black hole wandering through space, having escaped the gravitational "gravitational bonds" of its host galaxy. The study was based on an analysis of data from the James Webb Space Telescope and concludes that this cosmic Leviathan, with a mass at least 10 million times greater than that of the Sun, is traversing intergalactic space at the astonishing speed of 1,000 km/s!
The possible discovery of this runaway galactic black hole was first announced in 2023 by Pieter van Dokkum of Yale University. While studying an image from the Hubble Space Telescope’s photo archive, van Dokkum had concluded at the time that a strangely thin but extremely extensive “structure,” stretching from its host galaxy over the vast distance of 200,000 light-years, could be indirect evidence of the existence of a colossal black hole that had escaped its gravitational pull.
In other words, as the black hole moves at high speed through intergalactic space, it “pushes,” compresses, and heats the intergalactic matter it encounters along its path, forming what is known as a bow shock at its leading edge. This compression of intergalactic gas and dust triggers multiple and continuous episodes of star formation, which have so far led to the formation of new stars with a total mass of 100 million solar masses. In other words, the thin structure that “bridges” the spatial gap between the host galaxy and the black hole consists of newborn stars that formed along its path.
With masses even billions of times greater than that of the Sun, supermassive black holes are found at the centers of most, if not all, galaxies in the Universe. In this particular case, however, the black hole has moved more than 200,000 light-years away from its host galaxy.
As it travels through intergalactic space, the black hole “pushes” the gas it encounters at speeds of hundreds of km/s. As van Dokkum explains, “the velocity of the ejected gas is directly related to the velocity of the black hole, and that is how we determined its speed … a particularly high speed that allowed it to escape the gravitational pull of its host galaxy”.
Generally speaking, there are two physical mechanisms that could eject a galactic black hole from its galaxy. As a general rule, when two galaxies collide and eventually merge, their respective supermassive black holes gradually shift toward the center of the new galaxy that forms in place of the two others. As they spiral closer and closer to one another, they eventually collide and merge into a new black hole, releasing gravitational waves that may send it hurtling away. This is the first mechanism.
The second mechanism that could eject a black hole from its galaxy is the interaction of three black holes, which can occur if one of the two colliding galaxies hosts not one, but two black holes in its core. In this case, that is, when a third galactic black hole approaches the binary black-hole system of the first galaxy, that system becomes unstable, and one of the three black holes—usually the one with the smallest mass—may be ejected. In fact, if the velocity imparted to it exceeds the escape velocity, then it will leave the galaxy and continue traveling through intergalactic space.
The possible escape of a giant black hole from its host galaxy has been predicted theoretically for many years. According to the researchers behind the study, however, this is the first time that the “escape” of a black hole from its host galaxy has been confirmed through observation.
This new study was posted on December 3, 2025, on the preprint server Arxiv and has been submitted for publication in the scientific journal *Astrophysical Journal Letters*.
Photo: This image from the Hubble Space Telescope's photo archive shows a strange linear structure 200,000 light-years long. Subsequent observations revealed that this structure consists of newborn blue stars. The supermassive black hole is located at the edge of this structure, at the bottom left, and was ejected from its galaxy, which is in the upper right corner [Credit: NASA, ESA, Pieter van Dokkum (Yale); Image Processing: Joseph DePasquale (STScI)].
Source: JWST Confirmation of a Runaway Supermassive Black Hole via Its Supersonic Bow Shock