A rogue black hole of unusual size is devouring stars in a distant galaxy

The discovery of a rogue supermassive black hole consuming a star 600 million light-years away has piqued the interest of astronomers worldwide. Named AT2024tvd, this event was first detected by the Palomar Observatory’s Zwicky Transient Facility and was later confirmed by the Hubble and Chandra space telescopes. These instruments helped pinpoint the location of this cosmic event. Astronomers were surprised to find that the black hole was not located at the center of its galaxy, which is the usual position for such massive objects, but instead was 2,600 light-years away from the galaxy’s center. This distance is about one-tenth of the distance between the Sun and the Milky Way's central black hole, Sagittarius A*.

Six panels (clockwise) show a black hole consuming a star, forming a bright disk, and emitting light, with a galaxy in the background. Illustration: NASA, ESA, STScI, Ralf Crawford (STScI)

The event AT2024tvd sheds light on a peculiar phenomenon known as a tidal disruption event (TDE), which occurs when a star gets too close to a black hole. The black hole’s immense gravity pulls on the star so intensely that it stretches, shreds, and ultimately spirals into the black hole. This violent interaction releases a spectacular burst of energy, which can be as bright as a supernova, making it visible across the electromagnetic spectrum. Consequently, TDEs present a unique opportunity to study black holes that might otherwise be dormant or obscured.

Researchers published their findings in a forthcoming paper in The Astrophysical Journal Letters, noting AT2024tvd as the first offset TDE discovered using optical surveys. Lead author Yuhan Yao from UC Berkeley suggests that TDEs have significant potential for revealing massive black holes that lie outside galactic centers. “Theorists have predicted a population of massive black holes located away from the centers of galaxies must exist, but now we can use TDEs to find them,” said co-author Ryan Chornock in a NASA release.

Astronomers have proposed several theories regarding how this rogue black hole might have come to rest so far from its galaxy's core. One explanation is that the black hole was once the central feature of a smaller galaxy that merged with a larger one. Another suggestion is a dynamic interaction where the black hole, part of a three-body system, was flung out by larger black holes. “If the black hole went through a triple interaction with two other black holes in the galaxy’s core, it can still remain bound to the galaxy, orbiting around the central region,“ according to Yuhan Yao.

Future observations with next-generation instruments like the Vera Rubin Observatory and the Roman Space Telescope may enable further discoveries of similar rogue black holes. These advancements could open up a new realm of understanding about how supermassive black holes move and interact within galaxies, challenging existing perceptions of black hole dynamics and offering deeper insight into the cosmic behavior of these powerful entities.

Sources: Gizmodo, NASA, arXiv