A 600 million light-year-away supermassive black hole is emerging

A newly discovered astronomical event known as AT2024tvd has led scientists to uncover a supermassive black hole in an unusual location. This phenomenon, called a tidal disruption event (TDE), occurs when a star ventures too close to a black hole and is violently pulled apart by its immense gravitational forces. According to Dr. Yuhan Yao of the University of California, Berkeley, the shredded remains of the star spiral into orbit around the black hole, generating shock waves and high-energy outflows visible in ultraviolet and optical light.

What makes this TDE exceptional is its discovery of a wandering supermassive black hole not located at the galaxy’s center-where such massive objects are typically found-but instead offset from it. The off-center position of the black hole was confirmed by astronomers using the NASA/ESA Hubble Space Telescope, with the help of data from NRAO’s Very Large Array and NASA’s Chandra X-Ray Observatory. Remarkably, this marks the first time an offset TDE has been observed out of around 100 recorded by optical sky surveys.

The black hole involved in AT2024tvd is about one million times the mass of our Sun and lies just 2,600 light-years from the galaxy’s central black hole, which is far more massive-around 100 million solar masses-and actively accreting gas as an active galactic nucleus. The distance between the two black holes prevents them from orbiting each other as a binary system, even if they are both located in the same galaxy. Over time, the smaller black hole might drift inward and merge with its larger counterpart, but for now, they remain independent.

Astronomers believe the off-center black hole may have been displaced by a past three-body gravitational interaction, where the lightest of three black holes is flung away from the core. On the other hand, it might represent the remains of a smaller galaxy that left its central black hole behind when it merged with the host galaxy more than a billion years ago.

Dr. Yao suggests that this groundbreaking observation will spark new efforts to search for similar wandering black holes. As Dr. Erica Hammerstein also from UC Berkeley noted, the presence of a second black hole offers compelling evidence of a past galactic merger, which may have also increased the rate of such tidal disruption events.