A Naked Black Hole Is Screaming Through the Universe (gizmodo.com) 99
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."
Fatties (Score:4, Funny)
Why is it the heavier they are the more they like running around naked?
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And how come you can hear them screaming if they're in space?
Black holes orbiting each other? (Score:1)
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.
I don't see how this can be true. If our galaxy collided with another, both black holes would plough on, on their own trajectories. Even if they came close enough to interact, they would be well above each other's escape velocity and so would continue while the gas clouds in their galaxies formed a new galaxy.
Re:Black holes orbiting each other? (Score:4, Informative)
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.
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By definition, objects a long distance from each other are outside each other's escape velocity. Earth and Mars, for example would never go into orbit around each other without the influence of a larger object like Jupiter or the sun. This is the starting condition for the two black holes.
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"By definition, objects a long distance from each other are outside each other's escape velocity"
Excellent. So we don't need to worry about the Death Asteroid.
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It depends on their relative speed if they would get into orbit of each other - low relative speed and no other significant mass nearby disturbing the balance and you would get them to act as a pair of dancers rotating around each other - even if it's going to be slow it would happen.
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They're not outside the escape velocity of the sum of the two entire galaxies. So they'll both stay in some orbit within the combined galaxy.
As they do, they keep encountering smaller star systems, which often get flung off in random directions. The net effect of these random encounters is to slow down both black holes relative to the center of mass of the combined galaxy, similar to friction. As they slow down, they sink towards the center. Eventually, they fall into orbit around each other and continued "
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For a planet like earth, the orbital velocity is much greater than the escape velocity, even at the surface.
But galaxies are different. The speed of the milky way relative to the CMB is about the same as its escape velocity from here.
So it is very easy for two galaxies to collide at less than their escape velocity. The time-scale is tens of millions of years, at least.
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Indeed if two black holes started very far away from each other and never passed so close to each other that newtonian approximation breaks down _and_ in empty space this would be true. However they are not in empty space but pass thru both galaxies flinging stars to very energetic orbits as they go. This is called dynamical friction and is usually enough to bind the two black holes.
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It's still quite interesting that the black hole got accelerated to such a speed, and only reason I can see for it is that it had a near miss with another much heavier black hole.
Imagine the bang when it finally hits something heavier than itself.
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May be it stole something?
Re:Black holes orbiting each other? (Score:5, Funny)
we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it.
Sounds like a standard relationship breakup to me...
Re: Black holes orbiting each other? (Score:1)
It's the same situation with asteroids and ice comets colliding. A head on collision would be an instant joining. A head-on near miss and they just carry on in slightly modified orbits. If the collision happens because rhe one behind is moving faster than the one in front then the relative speed is the difference in velocities. That allows everything to happen slowly.
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Galaxies typically form in gravitationally-bound clusters. and the super-massive black holes form at the centre of the galaxies; i.e. they co-move with the galaxies. If two galaxies from the same cluster merge, the holes at their cores do not have relative escape-velocity and end up gravitationally bound.
The interesting point in the current story is that the black hole has picked up much more velocity and escaped. I.e. it is exceptional.
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Would this produce any gravity waves that we can detect?
No this would not be possible with 2016 technology already built and running. It would produce extremely faint waves each time the black holes moved by each other. Likely this happened because this hole was significantly less massive than the other black hole and got a lucky slingshot style flyby when they came near much like spacecraft use today to increase thier speed.
Gravitational waves are so difficult to detect it is only in the final interaction where they are orbiting eachother many times a secon
Re:Never stop? (Score:5, Funny)
Screaming through the universe?
In space no one can hear you scream.
Re:Never stop? (Score:4, Interesting)
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When I first saw the headline, I thought they were talking about a Naked Singularity [wikipedia.org]. Now that would have been interesting.
That's what I thought too.
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Agreed, this seemed deliberately click-baity to me (and it worked!)
I've never heard the term naked black hole before.
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It's not even moving. (Score:2)
It's a bum rap. THe rest of the universe is moving. It's staying still.
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Even worse: you don't want to draw it's attention; it might want to come over and talk to you.
Don't anthropomorphize objects -- they HATE that.
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The black hole isn't screaming, it's the victims.
Ah yes, inescapable gravitation... (Score:2)
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.
That's how I met my girlfriend.
Averting my eyes (Score:1, Funny)
millions of years ago? (Score:3)
The collision must have happened more than 2 billion years ago, or we wouldn't know about it yet.
Speaking of galactic collisions, theres a new eBook out from Ian Douglas called Altered Starscape
(Ian Douglas is the author of the Star Carrier series and also writes under his real name of William H Keith)
This new series is called "Andromeda Dark" so its probably not much of a spoiler to tell you that the other galaxy involved is M31
Highly recommended for fans of Space Fleet / Galactic Empire science fiction
Dumb headline (Score:2, Funny)
I would have thought "A Naked Black Hole Is STREAKING Through the Universe" would have been the obvious headline.
On the other hand I grew up in the 60's-70's...
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I would have thought "A Naked Black Hole Is STREAKING Through the Universe" would have been the obvious headline.
On the other hand I grew up in the 60's-70's...
Oh, that would have been good!
Annoying title, as usual (Score:1)
The title of this post is annoying. As is usually the case these days, of course.
But in this case it's particularly annoying since it "hints" at this being at least related to a naked singularity. Something which would be very interesting indeed.
And "screaming"? At 2000 km/s? No.
Bad Slashdot.
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Pls mod parent up.
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Almost 1/100th of the speed of light, which is quite fast. Fast enough to get relativistic effects.
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The headline annoyed the fuck out of me when I saw it in Google Science News. So I looked it up on Arxiv (costing Giz ... whoever they were ... some eyeball-seconds).
Link to original paper [arxiv.org]. Link to PDF. [arxiv.org]
Abstract.
During a systematic search for supermassive black holes (SMBHs) not in galactic nuclei, we identified the compact symmetric radio source B3 1715+425 with an emission-line galaxy offset ~8.5 kpc from the nucleus o
Naked Black Hole? (Score:2)
s/Screaming/Streaking/
A Naked Black Hole Is Streaking Through the Universe
There, that's better.
Serious question here. (Score:2)
Re: Serious question here. (Score:1)
It could be detected when it occludes or distorts the light of objects behind it.
Isn't this just a regular black hole? (Score:5, Informative)
Just a regular, hairless [wikipedia.org] yet non-naked black hole. That's what it sounds like.
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That is due to improperly sufficient wiping.
Re:Isn't this just a regular black hole? (Score:5, Funny)
lets just say a scantily clad blackhole
Re:Isn't this just a regular black hole? (Score:4, Insightful)
I thought the same thing at first reading of the title but the wording involved has a subtle distinction. A "naked singularity" is a term which has been defined by physicists for a while and is, as you stated, a singularity in space-time which does not have an event horizon around it, or would be if such a thing can exist, which is currently undecided. The presence of an event horizon is what makes a black hole (things go in, nothing comes out [minus Hawking radiation, I know]). The term "naked black hole" seems to be a term just made up by the author of the linked article or somewhere back in the reporting chain and has no formal definition, as far as I know, but is highly misleading. I would say that whoever made up that term "naked black hole" is not very familiar with the field of gravitation or they would have avoided this confusing construction. Speaking of confusing, the last time I posted something involving General Relativity, I screwed it up; hopefully this time is better.
Don't look, Ethel! (Score:2)
...but it was too late.
Streaking away (Score:1)
Great! (Score:2)
Where do I point my telescope?
Can someone explain this to me? (Score:2)
So, the name black hole comes from the fact that this object is so massive, nothing can escape its gravitational pull, even light. So, how is it "belching deadly x-rays" or even "hemorrhaging ionized gas"?! Would something escaping it render this object not a black hole any more?
Re:Can someone explain this to me? (Score:5, Informative)
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.
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I"it may never stop"...stop relative to what?
And don't forget, "2,000 kilometers per second" ... relative to what?
Oh, it's just killing me (Score:1)
Must...resist...Trump...joke
A Naked Black Hole? (Score:1)
The Playboy web site will have to start an astronomy section.
But but but... (Score:2)
In space, no one can hear you scream.
Shouldn't that be "Streaking Through the Universe" (Score:2)
Please? (Score:2)
The working theory is that (it) got shredded to bits, a bit like a paper airplane flying into a hurricane. The leftovers include... the supermassive black hole itself
Please can we call it Goatse?