＂Out of control＂ black holes run away from the host galaxy.

　　The runaway black hole escapes from its host galaxy (art picture).

　　Image source: NASA/European Space Agency

　　Science and Technology Daily, Beijing, April 11th (Reporter Liu Xia) According to a report by the American Fun Science Network on the 10th, American astronomers have discovered a "runaway" black hole, which seems to be escaping from its host galaxy and running wildly in space, dragging some gases and stars behind it. The research team pointed out that if this discovery is confirmed, it will be the first observational evidence that supermassive black holes can be ejected from their host galaxies and roam in interstellar space. Related research was published in the latest issue of Astrophysics Journal Express.

　　When the researchers used the Hubble Space Telescope to observe the dwarf galaxy RCP 28 about 7.5 billion light-years away from the Earth, they found this "runaway" black hole, which showed a bright stripe. Subsequent observations show that this stripe is more than 200,000 light years long, about twice the width of the Milky Way, and is composed of compressed gas that forms stars. The stripes point right at the center of the galaxy, which is usually the "site" of supermassive black holes.

　　The research team estimates that the black hole is about 20 million times the mass of the sun and is leaving its host galaxy at a speed of 5.6 million km/h.

　　Peter Van Dokum, a professor of physics and astronomy at Yale University, the main author of the study, pointed out that they found a thin line pointing to the center of the galaxy in the image of the Hubble Space Telescope, and then they used the Keck Telescope in Hawaii to find that this line is connected with the galaxy. Detailed analysis shows that a huge black hole is being ejected from the galaxy, dragging gas and newly formed stars on the "tail". If this inference is confirmed, it will be the first time that scientists have clear evidence that supermassive black holes can escape from galaxies.

　　Dokum explained that when three objects with similar mass interact with each other because of gravity, the two objects will "join hands" and the third object will "eject". This may mean that this "out of control" black hole was once part of a pair of rare supermassive black holes. During the merger of galaxies, the third supermassive black hole "intruded" and "expelled" one of them.

　　Dokum said that the ejection of supermassive black holes from galaxies has been predicted for 50 years, but so far scientists have not clearly observed such phenomena. They also need to use other telescopes to further observe and find direct evidence of this black hole.