Dormant supermassive black hole found 30,000 light-years from galaxy

A dormant supermassive black hole located far from the center of its galaxy has been discovered by University of Maryland astronomers, as reported on August 6, 2026. The finding, published in The Astrophysical Journal Letters on July 27, 2026, marks the first time an inactive black hole has been found at such a distance from a galactic core.

The black hole was revealed when it tore apart a passing star, producing a brief, intense flare of light. Because it was not actively consuming matter, it would have remained invisible otherwise. Study co-author Suvi Gezari, an associate professor of astronomy at UMD, said the discovery challenges the assumption that supermassive black holes reside only in galactic centers and will lead to finding many more wandering black holes.

The object sits 9.3 kiloparsecs, or about 30,000 light-years, from its galaxy's center, with a mass comparable to the Milky Way's central black hole. UMD Astronomy Professor Sylvain Veilleux noted the puzzling lack of a visible galaxy around it, suggesting a past galactic collision may have stripped away stars, leaving only the core and black hole. Another possibility is a three-body black hole interaction that ejected the smallest one.

Researchers detected the event using the Zwicky Transient Facility at Palomar Observatory, which surveys the entire northern sky every two days. To handle the massive data, they created an AI program trained to recognize tidal disruption events—the light pattern from a star being destroyed by a black hole. The system began operating in August 2025 and identified the wandering black hole just three months later, according to study lead author Robert David Stein, a Neil Gehrels Prize Postdoctoral Fellow at the Joint Space-Science Institute.

Stein recalled the discovery moment vividly, noting the team quickly triggered other instruments for more data. The research, funded by the U.S. National Science Foundation and other organizations, demonstrates that machine learning can open new research areas. Future searches with the NSF-DOE Vera C. Rubin Observatory in Chile, which debuted last June, could find dozens or hundreds of wandering black holes annually, Stein expects.

Veilleux highlighted the Lowell Discovery Telescope's new spectrometer, a collaboration between GSFC, UMD, and Lowell Observatory, which may detect tidal disruption events at greater distances. He called this the strongest case of a wandering black hole, setting a standard for future discoveries. The team continues searching for more such objects to understand galaxy formation and black hole mergers.