Astronomers have spotted a tightly coupled pair of supermassive black holes. They call this pair of giant black holes J0045+41.

Astronomers observed it using X-ray data from NASA’s Chandra X-ray Observatory and optical data from ground-based telescopes.

Previously, researchers thought this object to be a binary star system, part of Andromeda. However, the new work shows they are two supermassive black holes orbiting one another extremely close, billions of light-years away.

“We were looking for a special type of star in the Andromeda Galaxy and thought we had found one. We were surprised and excited to find something far stranger,” said Dr. Trevor Dorn-Wallenstein, from the University of Washington.

“This is the first time such strong evidence has been found for a pair of orbiting giant black holes,” said Dr. Emily Levesque, also from the University of Washington.

The work is published online at

The total mass of the two supermassive black holes, researchers estimate, is around 200 million solar masses.

Firstly, researchers combined the Chandra X-ray Observatory data with spectra from the Gemini North telescope in Hawaii. Thus, showing that J0045+41 likely contained at least one supermassive black hole.

However, through data from the Palomar Transient Factory telescopes in California, the research team found repeating variations in the light from J0045+41. Thereby, showing the presence of two black holes orbiting each other.


Researchers think such a system could be formed from the merger of two galaxies, both containing a supermassive black hole. The merging could have happened billions of years earlier.

Current proximity tells us the pair is getting closer and closer.

“We’re unable to pinpoint exactly how much mass each of these black holes contains. Depending on that, we think this pair will collide and merge into one black hole in as little as 350 years or as much as 360,000 years,” said Dr. John Ruan, also of the University of Washington.

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Thumbnail Image: X-ray source LGGS J004527.30+413254.3. Credit: NASA / CXC / University of Washington / T. Dorn-Wallenstein et al / ESA / J. Dalcanton et al / R. Gendler