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A Naked Black Hole Is Screaming Through the Universe (gizmodo.com)
New submitter PongoX11 writes: Millions of years ago, B3 1715+425 was just an ordinary supermassive black hole. It had a comfortable life, of devouring stars and belching deadly x-rays, at the center of its distant galaxy. Now, starless and alone, it's screaming through space at 2,000 kilometers per second -- and it may never stop. BC 1715+425's troubles began when its galaxy bumped up against another. This isn't all that unusual: in fact, astronomers believe that the largest galaxies in our universe formed during ancient mergers. Normally, when two galaxies collide, the supermassive black holes at their centers start to orbit one another, moving closer and closer together in an inescapable gravitational attraction. Eventually, those black holes can fuse, releasing a burst of energy as gravitational waves and completing the cosmic joining. Most of the time, this process seems to work out for all parties involved, judging from the fact that nearly all supermassive black holes reside at the center of galaxies, and nearly all galactic centers contain a supermassive black hole. But every now and then, something goes wrong and cosmic wreckage ensues. B3 1715+425, speeding away from the core of a bloated galactic merger 2 billion light years from Earth, is living proof of this. The working theory is that millions of years ago, B3 1715+425's galaxy passed through a much larger galaxy (one that had formed during many previous mergers) and got shredded to bits, a bit like a paper airplane flying into a hurricane. The leftovers include a faint galactic remnant, just 3,000 light years across, and the supermassive black hole itself, nearly naked and hemorrhaging ionized gas as it tears through the void. "We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger," said James Condon, the astronomer at the National Radio Astronomy Observatory who led the study. "Instead, we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it."
How do you know that? Their relative velocity would depend on how fast the galaxies were moving together, and the escape velocities would depend on how close they passed by one another.
Sheesh, evil *and* a jerk. -- Jade
Um, a naked black hole is actually a very specific thing (a singularity without an event horizon) that may or may not even exist in nature. Just skimming the article, this sounds like an ordinary black hole to me.
Just a regular, hairless yet non-naked black hole. That's what it sounds like.
It's just a really, really terribly written article.
There is a theoretical object called a "naked singularity", a black hole without an event horizon, which stuff actually would be able to escape from. This isn't one of those. The author's calling it "naked" because it doesn't have any of the usual stuff around it...except it's not even that. It's the remnants of the core of a galaxy: a few thousand stars, some gas, and a black hole. The x-rays come from surrounding debris falling into it, not the black hole itself. The black hole isn't hemorrhaging anything, the gas is just debris that the core wasn't able to hold onto after the collision that stripped most of the rest of its stars and gas away. It doesn't even mean anything to say "it may never stop"...stop relative to what?
It's just sensationalized gibberish.