In a discovery more than a decade in the making astronomers have directly observed a pair of supermassive black holes orbiting one another. Using the powerful radio “vision” of the National Science Foundation’s very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth. If confirmed with follow-up research, this will be the first time two black holes have ever been seen moving in relation to one another.

University of New Mexico Department of Physics & Astronomy graduate student Karishma Bansal, along with UNM Professor Greg Taylor and colleagues at Stanford wrote the paper, ‘Constraining the Orbit of the Supermassive Black Hole Binary 0402+379’, recently published in The Astrophysical Journal. The UNM team, along with the U.S. Naval Observatory and the Gemini Observatory, have been studying the interaction between these black holes for 12 years. The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.

The tremendous size of these two black holes means there is a lot of ground to cover in their orbital period, which actually takes around 24,000 years to complete. So while the team has been observing them for 12 years, the orbit is projected and not really seen as the movement has been measured at a snails pace of 1 cm per second. The research team will take another measurement of the locked in black hole pair in three or four years to confirm the motion and obtain a more precise orbit.