“We may be observing the aftermath of two supermassive black holes merging,” said Jim Condon, a radio astronomer at the National Radio Astronomy Observatory who was involved in the study. “The result of such a merger can cause the newborn black hole to recoil, and we may be watching it in the act of recoiling or as it settles down again.”

But there’s another, perhaps even more exciting possibility: the black hole may be part of a binary system.

“Despite every expectation that they really ought to be out there in some abundance, scientists have had a hard time identifying clear examples of binary supermassive black holes,” Pesce says. “What we could be seeing in the galaxy J0437+2456 is one of the black holes in such a pair, with the other remaining hidden to our radio observations because of its lack of maser emission.”

Further observations, however, will ultimately be needed to pin down the true cause of this supermassive black hole’s unusual motion.

Co-authors of the new study are Anil Seth of the University of Utah; Jenny Greene of Princeton University; Jim Braatz, Jim Condon, and Brian Kent of the National Radio Astronomy Observatory; and Davor Krajnović of the Leibniz Institute for Astrophysics in Potsdam, Germany.