(C) Daily Kos This story was originally published by Daily Kos and is unaltered. . . . . . . . . . . Top Comments: Runaway Supermassive Black Hole! [1] ['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.', 'Backgroundurl Avatar_Large', 'Nickname', 'Joined', 'Created_At', 'Story Count', 'N_Stories', 'Comment Count', 'N_Comments', 'Popular Tags'] Date: 2023-02-26 It probably doesn't look like this... ...maybe. The report is a preprint of a paper that is currently in peer review, but it looks exciting. More details after the public service announcement. Here at Top Comments we strive to nourish community by rounding up some of the site's best, funniest, most mojo'd & most informative commentary, and we depend on your help!! If you see a comment by another Kossack that deserves wider recognition, please send it either to topcomments at gmail or to the Top Comments group mailbox by 9:30pm Eastern. Please please please include a few words about why you sent it in as well as your user name (even if you think we know it already :-)), so we can credit you with the find! Black holes with masses greater than 100,000 times the mass of the Sun are designated supermassive. Such black holes are usually found at the centers of galaxies. With a fairly large density of matter (for interstellar space), it makes a good location for a black hole to form, and it then serves as the gravitational center of the galaxy. However, a question that some astrophysicists have considered is whether there might be supermassive black holes wandering outside of galaxies. Since the best environment for the formation of a supermassive black hole is at the center of a galaxy, how would a so-called “rogue” supermassive black hole come about? A proposed mechanism is through galactic collisions. When two galaxies collide, eventually, their respective supermassive black holes will find each other and form a stable orbit until, after a billion years or so, they merge into a single, even larger black hole. If, while they orbit, a third galaxy collides with the merged double galaxy, there will be three supermassive black holes interacting with each other, and the dynamics of such systems have long-term unpredictability built in. One outcome is that one of the black holes will ultimately be cast out of the combined galaxy to wander the clircumgalatic medium. (This is what the environment between galaxies is called. It’s my new word for the day.) Up to now, it has only been suggested that such rogue supermassive black holes might exist. Now, a collaborative of researchers in the U. S., Canada and Australia think they’ve found one. Finding such an object is challenging. Black holes only emit light when they are devouring matter, and there’s not much matter in the circumgalactic medium. However, a supermassive black hole flung out of its galaxy will propagate shock waves through whatever matter happens to be present, and the consequences are likely to be visible. That’s how the researchers were able to identify their candidate runaway black hole. Credit: van Dokkum et al. 2023 The photo to the right is an image from the Hubble Space Telescope’s Advanced Camera for Surveys. The candidate supermassive black hole is 230 million light years away. The clue that there is such a black hole in this vicinity is the line of stars. The shock wave set off by the passage of the black hole initiated star formation in its wake. Analysis of the light from these stars confirm that they are young (less than 30 million years old) and have the properties expected for stars formed in this medium. Further, the rogue black hole’s host galaxy is also expected to show signs of disruption, as a galaxy can’t eject an object so massive without shaking up the neighborhood significantly. This black hole’s previous host galaxy shows signs of just that sort of disruption. So it looks like runaway supermassive black holes are actually a thing. I wouldn’t worry too much about one showing up in our neighborhood if I were you. They’re bound to be pretty rare, and if one is headed our way, there’s bound to be some kind of warning. Comments are below the fold. [END] --- [1] Url: https://www.dailykos.com/stories/2023/2/26/2155147/-Top-Comments-Runaway-Supermassive-Black-Hole Published and (C) by Daily Kos Content appears here under this condition or license: Site content may be used for any purpose without permission unless otherwise specified. via Magical.Fish Gopher News Feeds: gopher://magical.fish/1/feeds/news/dailykos/