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Harvard researchers have found evidence that supermassive black holes move, according to a study published in The Astrophysical Journal last week.
The study was conducted by researchers at the Center for Astrophysics | Harvard & Smithsonian, the National Radio Astronomy Observatory, Princeton University, the University of Utah, and the Leibniz Institute for Astrophysics in Potsdam, Germany.
The researchers compared the velocities of several black holes with the velocities of the galaxies in which they are situated. The results showed that for one of the galaxies, the stars and gas at its center were not moving at the same velocity as its black hole, suggesting that the black hole was moving independently of the galaxy.
Dominic W. “Dom” Pesce ’12, a Harvard postdoctoral fellow who led the study, wrote in an email that this independent movement implies the supermassive black hole has interacted with another black hole of a similar mass.
“An SMBH that is moving with respect to its host galaxy is a strong indication that the system is either about to experience a SMBH binary merger, or that it has recently done so,” Pesce wrote. “Either scenario provides exciting indirect evidence for the reality of SMBH merger events — which have yet to be directly detected — and therefore also evidence of a specific mechanism for SMBH growth.”
Co-author and astronomer James A. “Jim” Braatz also proffered his assessment of the supermassive black hole.
“The nature of that interaction is probably related to a merger of galaxies. In other words, there was probably another galaxy that kind of swung close to this one. It also had a black hole in its center and those black holes interacted and they can kind of give each other a gravitational kick and move away from center,” he said.
Scientists have long posited the presence of supermassive black holes that move relative to their galaxies but have had trouble observing them clearly up until now.
“This galaxy where we actually see the black hole moving relative to the galaxy is very exciting because people have been looking for these cases for a long time,” according to Jenny E. Greene, a co-author and a professor of astrophysical sciences at Princeton.
Moving forward, Pesce said the team will search through data gathered from a network of space and Earth based radio antennae for emissions from another supermassive black hole.
Greene said there are “two paths” for future inquiry.
“One is to dig deeper on this galaxy and try to figure out what happened in its past to cause this black hole to be moving,” she said. “The other big challenge is to find more cases of moving black holes.”
—Staff writer Mayesha R. Soshi can be reached at mayesha.soshi@thecrimson.com.
