Astronomers have discovered for the first time a pair of supermassive black holes that are slowly orbiting each other in the center of a galaxy 750 million light years away.
The black holes take 30,000 years to complete one orbit, scientists believe, and their presence together indicates that two galaxies likely merged together in the past, Astronomy.com reported. Such an occurrence had been theorized previously, but had never been observed until now.
The black holes are only 24 light-years apart, and their combined mass is 15 billion times greater than our sun’s, Astronomy.com reported. In time, the two black holes are expected to combine into a single object. Black holes have much greater mass than stars but are difficult to see and can often be detected only by their energy signatures or pull on nearby objects.
The size of the two black holes could even indicate that more than two galaxies had combined together to form the larger holes, Gizmodo reported.
Although the discovery is exciting, scientists want to continue studying the galaxy and others like it. “We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of black holes,” study author Greg Taylor of the University of New Mexico said in a press release, according to Astronomy.com.
The observation was made using the Very Long Baseline Array, a telescope system with locations across the U.S., Hawaii and the Caribbean, Gizmodo reported. It was the smallest motion ever observed in the sky.