JWST Confirms Runaway Supermassive Black Hole Escaping Galaxy at 2 Million MPH, Researchers Say
Astronomers have confirmed a supermassive black hole fleeing its host galaxy at about 2.2 million miles per hour, according to a preprint study released on arXiv on Dec. 3. Researchers led by Pieter van Dokkum at Yale University said the James Webb Space Telescope detected a bow shock as evidence. The black hole, with a mass between 10 million and 20 million times that of the sun, trails a 200,000-light-year-long wake of young stars. Observations captured light from 6.9 billion years ago, when the universe was half its current age of 13.8 billion years.
The discovery validates theories of runaway supermassive black holes proposed for 50 years, van Dokkum's team wrote in the preprint submitted to Astrophysical Journal Letters. Such black holes form during galaxy mergers through gravitational interactions that eject one at high speeds. Researchers first spotted the object in 2023 using archival Hubble Space Telescope images, which showed a faint linear feature. Follow-up observations with the Keck Observatory in Hawaii confirmed details, but JWST provided the key infrared detection of the bow shock, indicating the black hole compresses gas ahead of it.
The black hole moves at 1,000 kilometers per second, equivalent to 3,000 times the speed of sound at sea level on Earth, according to the study. This speed ranks it among the fastest-moving objects detected, researchers said. The star trail spans twice the diameter of the Milky Way galaxy. Van Dokkum described the bow shock as "smoking-gun" proof in a statement reported by Live Science. "We suspected that this strange object might be a runaway supermassive black hole, but we did not have 'smoking gun' proof," van Dokkum said. "JWST's sensitivity and sharpness shows the bow shock."
The object resides in a pair of merging galaxies nicknamed the Cosmic Owl, NASA officials said. Light from the event traveled across half the universe to reach telescopes. The preprint has not undergone peer review yet, van Dokkum's team noted. Researchers called for searches for more examples to build on this potential first confirmation. "The obvious next step is to look for more examples," van Dokkum said, according to Space.com.
Prior candidates for runaway black holes existed but lacked direct evidence like the bow shock and star wake, the study stated. Theories suggest three-body interactions in binary black hole pairs during mergers cause the ejections. This case arose from such a merger, compressing gas to trigger star formation in the trail, researchers explained.
JWST, launched in 2021 by NASA and the European Space Agency, enabled the detection through its infrared capabilities. Hubble provided initial visible-light images, while Keck supplied spectroscopic data for mass and velocity estimates. The mass range of 10 million to 20 million solar masses reflects variations in early reports, with the preprint expected to clarify the figure upon review.
The finding advances understanding of black hole and galaxy co-evolution, van Dokkum's team wrote. It reveals dynamics in early universe mergers and could explain wandering black holes. The discovery aligns with recent black hole research, including gravitational wave detections by LIGO and images from the Event Horizon Telescope.
Astronomers anticipate more such findings as JWST continues observations. Van Dokkum has authored prior peer-reviewed papers on supermassive black holes, according to Yale University records. The team plans to seek additional data to refine measurements.
No official name or exact coordinates appear in public sources, but the preprint on arXiv provides details for verification. Researchers urged caution, noting the study remains preliminary until peer-reviewed.
