May 25, 2010
Supermassive Black Holes May Frequently Roam Galaxy Centers
MELBOURNE, FLA.—A team of astronomy researchers at Florida Institute of Technology and Rochester Institute of Technology in the United States and University of Sussex in the United Kingdom, find that the supermassive black hole (SMBH) at the center of the most massive local galaxy (M87) is not where it was expected. Their research, conducted using the Hubble Space Telescope (HST), concludes that the SMBH in M87 is displaced from the galaxy center.
The most likely cause for this SMBH to be off center is a previous merger between two older, less massive, SMBHs. “We also find, however, that the iconic M87 jet may have pushed the SMBH away from the galaxy center,” said Daniel Batcheldor, Florida Tech assistant professor in the Department of Physics and Space Sciences, who led the investigation.
The study of M87 is part of a wider HST project directed by Andrew Robinson, professor of physics at RIT. “What may well be the most interesting thing about this work is the possibility that what we found is a signpost of a black hole merger, which is of interest to people looking for gravitational waves and for people modeling these systems as a demonstration that black holes really do merge,” says Robinson. “The theoretical prediction is that when two black holes merge, the newly combined black hole receives a ‘kick’ due to the emission of gravitational waves, which can displace it from the center of the galaxy.”
David Merritt, professor of physics at RIT, adds: “Once kicked, a supermassive black hole can take millions or billions of years to return to rest, especially at the center of a large, diffuse galaxy like M87. So searching for displacements is an effective way to constrain the merger history of galaxies.”
Jets, such as the one in M87, are commonly found in a class of objects called Active Galactic Nuclei. It is commonly believed that supermassive black holes can become active as a result of the merger between two galaxies, the infall of material into the center of the galaxy, and the subsequent merger between their black holes. Therefore, it is very possible that this finding could also be linked to how active galaxies—including quasars, the most luminous objects in the universe—are born and how their jets are formed.
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http://quasar.astro.fit.edu/~perlman/blackhole/BlackHolesRoamPressReleaseFINAL.pdf