Astronomers amazed to find supermassive black hole wandering aimlessly through space
Astronomers have spotted a black hole on the move.
Supermassive black holes generally stay put as they suck in everything that comes their way, but scientists have long thought it was possible for them to wander through space. They've just never properly caught one in the act — until now.
Researchers and the Center for Astrophysics | Harvard & Smithsonian have identified the clearest example yet of a black hole in motion, publishing their findings in The Astrophysical Journal. About 230 million light years away, at the center of a galaxy named J0437+2456, the team found what they were looking for.
"We don't expect the majority of supermassive black holes to be moving; they're usually content to just sit around," lead author Dominic Pesce said in a news release. "They're just so heavy that it's tough to get them going. Consider how much more difficult it is to kick a bowling ball into motion than it is to kick a soccer ball — realizing that in this case, the 'bowling ball' is several million times the mass of our Sun. That's going to require a pretty mighty kick."
The team has been studying 10 distant galaxies and their supermassive black holes, specifically ones containing water, for the past five years. They were able to precisely measure a black hole's velocity based on the water orbiting the black hole, which produces a measurable laser-like beam of radio light, known as a "maser."
"We asked: Are the velocities of the black holes the same as the velocities of the galaxies they reside in?" Pesce explained. "We expect them to have the same velocity. If they don't, that implies the black hole has been disturbed."
Nine of the 10 black holes were resting — but one appeared to be in motion.
Follow-up observations with the Arecibo Observatory in Puerto Rico, before its collapse, and the Gemini Observatory in Hawaii and Chile confirmed the findings: The black hole, which has a mass that is 3 million times that of our sun, is moving at about 110,000 miles per hour inside its galaxy.
Scientists have two theories for the wandering black hole. One possibility? A collision.
"We may be observing the aftermath of two supermassive black holes merging," said co-author Jim Condon. "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."
Scientists also think it's possible that the black hole is part of a pair.
"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."
More observations are needed to understand the true cause of the peculiar movement.