Astronomers have discovered a mammoth black hole fleeing its host galaxy at high speed, the galactic eviction they claim may be the result of a violent merger between two black holes.Most galaxies the size of our own Milky Way or larger are thought to harbour a supermassive black hole, weighing millions or billions of times as much as the Sun, at their centres. When galaxies merge, these black holes may spiral in towards one another and collide.Now, an international team, led by Stefanie Komossa of Max Planck Institute for Extraterrestrial Physics in Germany, has identified the first known case of a supermassive black hole flung from its host galaxy.The astronomers, who combed through observations of galaxies by the Sloan Digital Sky Survey, found the signature of an ejected supermassive black hole in the form of a quasar called SDSS J0927+2943, the ‘Astrophysical Journal’ reported.Quasars are extremely bright, compact objects thought to be galaxies in which a supermassive black hole is feeding at a prodigious rate and glowing brightly as a result.According to Komossa’s team, the black hole appears to be speeding through its host galaxy. That is based on two sets of bright lines in the quasar’s light spectrum - one appears to come from gas clouds within the galaxy, while the other is characteristic of matter orbiting a supermassive black hole.Based on the way the lines appear to be shifted by the Doppler effect, the team estimates the black hole is moving at 2650 kilometres per second relative to its host galaxy. At this speed, the black hole should one day escape the galaxy.“The result is just what one would expect if the black hole had undergone a recent merger that kicked it out of the galaxy at high speed, carrying some of the galaxy’s matter along with it.“SDSS J0927+2943 is the best candidate to date for a recoiling supermassive black hole,” Komossa wrote in the journal.
