Using NASA’s Hubble Space Telescope, astronomers pinpointed an invisible monster lurking 600 million light-years away, but not in any galactic center, where supermassive black holes are typically found. This sneaky black hole quietly devours stars that wander too close and surrounding material.
Its presence was exposed in a recent tidal disruption event (TDE) called AT2024tvd, where a doomed star was shredded and consumed, unleashing a brilliant burst of radiation. Most tidal disruption events (TDEs) occur near supermassive black holes at the centers of galaxies. Still, this newly identified offset TDE suggests a rogue black hole lurking outside a galactic core.
Hubble’s sharp vision revealed that the TDE occurred just 2,600 light-years from the galaxy’s central, larger black hole—only a tenth of the distance between our Sun and the Milky Way’s supermassive black hole.
The larger black hole is an active galactic nucleus, continuously consuming gas and releasing energy. Oddly, despite sharing the same galaxy, the two supermassive black holes aren’t gravitationally bound as a binary pair. The smaller one may eventually drift inward and merge with its massive counterpart, but it remains too distant for a gravitational lock.
The black hole’s feast was exposed when ground-based sky survey telescopes detected a flare as brilliant as a supernova. Unlike stellar explosions, this flare revealed a black hole devouring a star—its extreme heat and broad emission lines of hydrogen, helium, carbon, nitrogen, and silicon gave it away. The Zwicky Transient Facility at Caltech’s Palomar Observatory was the first to spot this cosmic event.
The team turned to NASA’s Chandra X-ray Observatory to pinpoint the flare’s exact location. The X-ray data confirmed that the flare wasn’t from the galaxy’s core. Still, they were offset, solidifying the discovery of a wandering black hole feasting away from the central supermassive black hole.
How did the black hole get off-center?
Some theories suggest black holes can be ejected from galaxy centers due to three-body interactions, where the smallest object gets kicked out. This could explain the wandering black hole near the galaxy’s core.
Another possibility is that the leftover remnant of a smaller galaxy merged with the host galaxy over a billion years ago. If that’s the case, it may eventually drift inward and merge with the central black hole, but its fate remains uncertain for now.
While Hubble images didn’t show clear signs of a past galaxy merger, researcher Erica Hammerstein noted that the presence of a second black hole suggests a merger must have happened at some point in the galaxy’s history.
Journal Reference:
- Yuhan Yao et al., A Massive Black Hole 0.8 kpc from the Host Nucleus Revealed by the Offset Tidal Disruption Event AT2024tvd, arXiv (2025). DOI: 10.48550/arxiv.2502.17661
