Pair of supermassive black holes share ‘meal’ for the first time

Galaxy 2MASX J21240027+340911 is known to have an active nucleus for about a decade. At its core, a supermassive black hole is absorbing interstellar matter, gas or dust, when it gets too close. Recently, astronomers detected a repeating signal from this object, suggesting a more complex structure: Not one, but two supermassive black holes located in the core of this galaxy – and they are sharing a meal together.

The total mass of this pair of black holes is 40 million times that of the Sun and they are about a light day apart, equivalent to about 26 billion km. This pair of black holes is predicted to collide in about 70,000 years, and they orbit each other closer and closer every 130 days. It is this orbital motion that produces the observed repeating phenomenon.

In the study published in the journal Astronomy & Astrophysics, lead author Lorena Hernández-García, an astrophysicist at the Millennium Institute of Astrophysics and Valparaíso University in Chile, said this was a very strange event. “We think that a gas cloud has enveloped the black holes. As they orbit each other, these black holes interact with the cloud, disturbing and consuming its gas. This creates a knife pattern motion in the light emitted from the system”.

The team considered many possibilities. That could be a common behavior in an operating kernel. Or, it could be a star that gets too close to the supermassive black hole, gets ripped apart, then slowly consumed. But a pair of supermassive black holes covered in a cloud of gas, “dining” while orbiting each other, is the most convincing hypothesis.

The team plans to continue monitoring this event to better model what is happening, as well as study the host galaxy undergoing the merger. This galaxy is 1 billion light years from Earth.