Why Some Supermassive Black Holes Have Big Jets 111
astroengine writes "Some of the supermassive black holes at the centers of galaxies have powerful jets blasting from their poles, and others have weak jets, but many don't have jets at all. Why is this the case? In new simulations carried out by astronomers at NASA and MIT, it would appear that the way in which the black hole spins relative to its accretion disk may be a contributing factor. Strangely enough, the results indicate that if the black hole rotates in the opposite direction to its accretion disk, the most powerful jets form. The region between the black hole event horizon and the accretion disk still baffles scientists, so these simulations are very speculative, but the results seem to match what radio astronomers are seeing in the cores of active galaxies. Perhaps it's time to fire up that event horizon telescope!"
Here's a silly question (Score:2)
Is there a name for the theory that all the missing dark matter is inside black holes?
P.S. Loved the mention of "space plasma" in TFA. It's not like regular plasma, it's space plasma.
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Re:Here's a silly question (Score:5, Interesting)
Is there a name for the theory that matter is being sucked out of our universe as fuel for another?
Kind of hard to reconcile since black holes increase in mass as they draw in matter (aka mass.)
Re:Here's a silly question (Score:5, Informative)
They also decrease in mass by emitting hawking radiation.
http://en.wikipedia.org/wiki/Hawking_radiation [wikipedia.org]
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Re:Here's a silly question (Score:5, Informative)
You may be thinking of the 'White Hole' theory.
http://curious.astro.cornell.edu/question.php?number=108 [cornell.edu]
http://en.wikipedia.org/wiki/White_hole [wikipedia.org]
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But the mass-energy remains constant. Loss of mass in black hole = gain of energy from emitted photons
Yes, it remains constant in the universe, not within the black hole. In fact given enough time without accreting new mass, the black hole will dissipate. This was the most brilliant (of a long list of other brilliant) conclusion Stephen Hawking arrived; Not even black holes are eternal in case the Universe expands forever (and we already proved it will expand forever).
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No black hole we can indirectly observe actually loses mass, though: it would have to be of less mass than the moon to overcome even the background cosmic radiation, let alone the radiation in the environments we're observing. The black holes at the center of galaxies, well, they won't even be evaporating when the universe is twice as old as it is now.
I guess I shouldn't be surprised that we'd cite wikipedia without reading or understanding it.
Re:Here's a silly question (Score:5, Interesting)
They increase in mass, yes but does their size increase? Where does the matter go if it's all compressed to a singularity? Are all the atoms just spaghettified, stacked one on top of the other in some infinitely tall, infinitely narrow well?
I have only a most basic grasp of cosmology but it's an interest of mine and I recall watching something on documentary heaven to the effect that black holes may well be a universe of their own. To be honest the very idea of a singularity still baffles me: it seems as though you start with an assemblage of simple, dull matter and in the blink of an eye any semblence to matter as we know it disappears and you're left with something that - to me at least - sounds like a feature of space itself.
Exactly what happens between the instant when you have a very, very dense lump of matter and an infinitely dense one? It seems an infantile question but where did all the matter go? Or was it transformed into something else that has mass but no size? Thinking about it gives me a headache and usually leaves me pondering whether any particles really have a physical size or if it's just another consequence of our limited view of the Universe.
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Well what you need to do is forget the idea of a "singularity" (a division by zero, etc.) that's just an artifact from the math, and we've shown (i believe) that the math breaks down after you hit the event horizon (and possibly at the event horizon, i don't recall correctly). What this means is that we have no way of knowing or understanding what happens to the matter there.
Re:Here's a silly question (Score:5, Interesting)
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In fact, tidal stresses will have reduced you to a fine red paste considerably before you even reach the event horizon. Cf Larry Niven's "Neutron Star"; while Niven's hero actually deals with a neutron star (as the story title implies) rather than a black hole, the same deal would exist with a black hole, only several orders of magnitude worse.
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Delta Tau^2 = (1-2M/r)dt^2 - dr^2/(1-2M/r)
Where Delta Tau is the invariant interval, 2M is the Distance from the singularity to the event horizon and r is the reduced circumference.
At the event horizon, where r = 2M, the equation breaks down.
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The math breaks down at the Event Horizon because of the expression
Delta Tau^2 = (1-2M/r)dt^2 - dr^2/(1-2M/r)
Where Delta Tau is the invariant interval, 2M is the Distance from the singularity to the event horizon and r is the reduced circumference.
At the event horizon, where r = 2M, the equation breaks down.
Neither the math nor the physics break down at the event horizon, the Schwarzschild coordinates does for that particular spacetime, but that's just a problem with Schwarzschild coordinates. Much in the same way polar coordinates are not well behaved at 0, but the space R^2 is. There are several ways to check this, you could calculate curvature invariantes like the Kretschmann invariant and check that it doesn't blow up there, or you could use another chart (Kruskal-Szekeres for example) which are perfectly
Good reading here (Score:5, Informative)
I have only a most basic grasp of cosmology but it's an interest of mine and I recall watching something on documentary heaven to the effect that black holes may well be a universe of their own
One of my most favorite books on the subject is called The Five Ages of the Universe [amazon.com] by Adams and Laughlin. If you like reading books about the subject but don't care about or can't comprehend the math, I seriously recommend it. That said (and I think it's in the book I linked), there's an evolutionary theory about universes that contends each time a black hole is created, it splits off a unique instance of spacetime creating a "new" universe with its own laws of physics. Universes created in this manner that contain laws of physics favorable to the creation of black holes will go on to evolve new "child universes" of their own; a sort of cosmic equivalent of Darwin's natural selection.
;)
One more thing, should you find yourself occasionally staring at the TV and wanting to feel educated and entertained, then you should, uh, "acquire" a copy of Into the Universe with Stephen Hawking [discovery.com]. It's a very well written and well narrated version of how Hawking explains the workings of the universe, but unfortunately isn't available on DVD yet. However, the trusty folks on the web that don't make any money from TV and movie distribution should have a copy you can pick up today
The extremely fun thing about physics from a layman's point of view is that there are so many theories about how the same things work, and getting them presented to you in a manner you can understand without knowing the math behind it is a wonderful thing. From there, you can theorize and come to your own conclusions about which you like best, because if Planck has anything to say about it, [wikipedia.org] we'll never truly know which of them is right.
It's kind of like going to a trade show, only instead of the place being full of vendors, it's full of missionaries from every major religion on the planet, and you get to objectively pick the one you like the best. I'm sure most Slashdotters would be drinking the free coffee at the Atheists' booth or ignoring everyone and speculating what the giant bundle of Cat5 on the wall goes to, but regardless of whether your God is supernatural or nonexistant, to glimpse into the very fabric and inner workings of the cosmos is the only true way to see into that mind.
Still, even if that's not the way you see it, I do feel that it's also the only way to even begin to fathom what we all really are.
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What happens when one black hole eats another?
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What happens when one black hole eats another?
Nothing special. The theory is that the "snap" happens at the moment a singularity is formed. It doesn't depend on it at all after that point.
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What happens when one black hole eats another?
I don't know, I'll tell you year after next.
M-Theory expansions (Score:1)
ITS entirely possible like whats obviousl and hte KISS idea of the most simple is most often the way things work.
IT is said there is a dimension where all gravity resides its one reason why gravity as a force is actually so weak. What maybe happening is that black holes are punching or getting back into that dimension but just cant quite get all way there c
Re:Here's a silly question (Score:5, Informative)
Yes, there is a direct relationship between the radius of the event horizon and the mass-energy within the event horizon. More massive or more energetic black holes have broader event horizons. This is observer dependent and subject to a Lorentz contraction, so if you are accelerating directly towards a black hole it will appear more massive (and thus have a larger radius) than if you are accelerating directly away from the same black hole; this effect increases exponentially as (absolute) relative velocity increases towards c.
When any observer sees mass-energy crossing into the event horizon, the event horizon's radius increases proportionately. Again an observer's measurement of that mass-energy is subject to a Lorentz contraction.
There is also an inverse relationship between the surface area of the black hole and its temperature; both are subject to the same Lorentz contraction, but more massive black holes emit photons similarly to colder blackbody radiators than less massive black holes.
We have no useful theory about what's going on the inside of an event horizon.
There are several ways to consider the microscopic states inside a black hole from a thermodynamics-meets-General-Relativity perspective. Here's one. In GR (and we have tested this), the lower the gravitational potential in which a clock is, the slower it ticks, for any form of clock (including naturally oscillating processes). Ignoring observers experiencing acceleration other than via gravitation, the gravitational potential is very high in inter-galactic-cluster space (i.e., farrrr away from dense mass-energy), lower inside solar systems, lower still on planetary surfaces, very low inside stars, and extremely low inside black holes. Consequently, a "clock" ticking inside a black hole will, from the perspective of someone with a high gravitational potential, tick very slowly. The "clock" itself, however, will always tick at its natural rate, from its perspective and the perspective of anything immediately near by it, unmoving, and at the same gravitational potential.
So from our perspective on Earth, a natural oscillator inside an event horizon will go from oscillating at, say, several GHz, to oscillating less than once every several billion years of our time.
From its perspective our clocks on Earth will speed up by the same factor.
However, where things get strange is where the gravitational potential changes in distances shorter than the wavelengths of protons, neutrons, electrons, photons, and so forth, since they are ultimately oscillating "clocks". If "part" of a proton is in a higher gravitational potential than the rest of it, how do the quarks and gluons within it behave? What happens to the proton? And so forth.
That requires a consistent unified theory of gravitation and quantum mechanics, which nobody has been able to demonstrate yet.
Electrons, Protons, and Neutrons obey Fermi-Dirac statistics for fermions. Spatially, this means that you can't stack them all in one place - there is a pressure separating fermions from one another. When you introduce pressure from, for example, gravitation in a heavy star, it overwhelms the fermionic pressure and creates "degenerate matter". Neutron stars have degenerate phases including neutrons formed by squashing together electrons and protons. Quark stars may exist, and would have degenerate phases formed by squashing together heavy (i.e., full of neutrons) atomic nuclei. Pressures at and inside an event horizon would almost certainly lead to some further degenerate phase, and we have no idea what happens then.
(We can somewhat reproduce some
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Actually, what more can I say? I think I'm love... always did have a thing for physicists.
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The only meaningful answer to measuring the size of a black hole is the radius of its event horizon, which depends solely on its mass, growing larger as the black hole's mass increases.
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Yes, but this is all determined by what happens outside the horizon. Anything which happens inside the horizon cannot affect anything observable, including the observed black hole mass, outside of the horizon of the black hole (neglecting Hawking radiation; if a black hole radiates away, I'm not sure if anything inside could be revealed).
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My understanding is that the mass of a black hole is the frozen gravity field that existed just as the event horizon formed.
I really don't get the physics, but I don't see any particular reason the matter/energy that created the singularity has to remain 'in the hole' once spacetime has been distorted so much that time has stopped. Its like gravity has got stuck trying to get out of the hole, so we dont need the original mass any more.
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It's probably in there somewhere.
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You're educated stupid bro, the "black hole" he stated in his stuff isn't a collapsed star...
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Re:Here's a silly question (Score:5, Informative)
MACHO: Massive compact halo object [wikipedia.org]
An alternate theory is WIMP [wikipedia.org]. You can imagine which ones the nerds prefer.
Wrong answered with wrong modded informative (Score:3, Informative)
For pity sake
1) The matter in a black hole isn't missing. It's accounted for. We can't know what kind of matter is in there because we can't know anything about stuff beyond the event horizon
2) We still don't know what Dark matter is, but we know that the so called WIMP model is most likely to account for most of it. We know this due to studies of objects like the bullet cluster of galaxies which can't be explained by MACHOs. In the bullet cluster, you see 2 galaxies that have collided - the normal matter i
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black holes do not absorb dark matter
http://www.universetoday.com/2010/03/22/astronomers-find-black-holes-do-not-absorb-dark-matter/#more-60422 [universetoday.com]
So this would suggest the darkmatter particle has no mass, travels faster than light or both?
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black holes do not absorb dark matter
http://www.universetoday.com/2010/03/22/astronomers-find-black-holes-do-not-absorb-dark-matter/#more-60422 [universetoday.com]
So this would suggest the darkmatter particle has no mass, travels faster than light or both?
I skimmed their journal article on arxiv. At this stage all they've shown is that there is an upper limit to the amount of matter in the central region of a galaxy given that we don't see a "runaway accretion" (presumably the whole galaxy goggled up by the black hole?). They conclude this suggests that the centers of galaxies have constant density.
So they seem to be saying dark matter doesn't live there (or that there is a limit to it) and that is how it avoids being sucked into the black hole.
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So this would suggest the darkmatter particle has no mass, travels faster than light or both?
Actually, none of the hypothesis. According to the article (and broader theory) it only means that either the distribution of dark matter in the galaxies is not has expected, or that it may be following a non Newtonian gravity law (yes, I know, we have something better than Newton laws nowadays, but the therm is used broadly to describe a theory in which the force of gravity doesn't decrease with the square root of the distance between masses).
think M-theory (Score:1)
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3) What's even more interesting is that recent work suggests black holes do not absorb dark matter
What's even more interesting is that your link doesn't suggest that black holes do not absorb dark matter:
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So essentially, you have a large sphere of dark matter on each side of the separating galaxies with all the regular matter between them.
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Doesn't dark matter have to interact via gravity in order to be responsible for the things it's claimed to be responsible for? If that's the case, why didn't it react with anything?
Right - it did react, but only gravitationally.
It's not as though the regular matter was interacting through electromagnetic, weak, or strong forces in any significant way during the collision. Gravity should have effected both types of matter equally, shouldn't it?
That's true for stars, planets, etc, but most of the bar
could that lend to the idea of it being (Score:1)
UGH ya my head is now starting to hurt too LOL
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Wow, thank you everyone for the interesting and informative posts on this thread. Great to see some signal in the noise.
are the jets tied to near by stargates? (Score:4, Funny)
are the jets tied to near by stargates?
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not for supergates (Score:2)
not for supergates
I found this article absorbing (Score:4, Funny)
I was completely sucked in.
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I guess you understand the gravity of the situation...
Are they jets or starships... (Score:1)
...and why do they need them?
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I was wondering the same thing the first time I saw Xenu's fleet. As to their purpose, ask Tom Cruise.
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This is Major Tom to Ground Control
I'm stepping through the door
And I'm floating in a most peculiar way
And the stars look very different today
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Not all galaxies are feeding, so it's not necessarily 10%.
As a random thought: Due to the twisting of spacetime that a spinning black hole generates (frame-dragging), objects rotating against the rotation are going to face a stronger gravitational pull than those moving with it, to the point where the nearby surrounding space is moving faster than light - the 'ergosphere'.
Since feeding black holes tend to shut down their own feeding, it might be the case that the resulting outward pressure pushes away matte
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It might be 50-50 to begin with. No clue why though.
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I'm not qualified to read this article. (Score:2)
My understanding was that black holes were a singularity. As for how something with no dimensions can spin, I am baffled. Perhaps my understanding of graduate level astrophysics is lagging a little.
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But it's weird since the singularity is an infinitesimal point, its angular velocity would be infinite wouldn't it?
Singularity of a rotating black hole might be a ring. At least the event horizon of a rotating black hole isn't a sphere. I think. Didn't check, may remember wrong...
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A black hole can have spin and charge, because these are both universally conversed quantities.
If a black hole is an empty region of space with a honking great curvature then where is the charge? If it's the result of charged matter taking forever to actually reach the singularity how can the mediator cross the event horizon? If it's matter outside the horizon, is it properly considered part of the black hole; I assume that virtual particles are released equally as far as charge is concerned? What, exactly, in a black hole carries the charge. Come to think about it, how can we know they're charged at
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What, exactly, in a black hole carries the charge.
I think it's related to the charge of the matter that's inside of it. Black hole eats 100 neutrons, 100 protons, and 99 electrons: positive charge.
It may not be that simple though, and I could be wrong. It's been a while.
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If I get your question right you want to understand how a black hole can hold charge and thereby influence things beyond the event horizon. Even though the event horizon prevents things inside from ever coming out again. It seems to me that if you assume the mass of a black hole is the property of only the matter inside it you have the same problem. Therefore it is better to consider the black hole as like a massive elementary particle from the out side which can have the following three properties; charge,
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If the spin of a black hole can be determined across a black hole, does that mean information can be transmitted across the event horizon?
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For a rotating black hole, the singularity is not a point, but a ring. [wikipedia.org]
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My understanding was that black holes were a singularity. As for how something with no dimensions can spin, I am baffled. Perhaps my understanding of graduate level astrophysics is lagging a little.
Interesting. My understanding of conservation of angular momentum makes me intuitive think the exact opposite: how could a zero-dimensional singularly have anything less than infinite spin? However, as has been noted elsewhere, the "singularity" in a rotating black hole is not zero-dimensional, as it forms a ring rather than a point, so the question is kinda moot.
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Wow, lots of responses.
My point was that many of us are armchair physicists. I don't know much about quantum theory or astrophysics other than the watered down versions of those subjects in popular press and on Wikipedia. Black holes are interesting and exciting, but I feel like a first grader hearing a description of calculus every time I read an article about them.
Too lazy to RTFA (Score:2)
All of this is /observed/ or /theorized/ behaviour ?
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The existence of the different jets is observed. The cause is theorized, but fits with observations.
I just assumed (Score:2)
That the supermassive black holes found that larger jets look slimming.
What's the big deal? (Score:5, Funny)
Some of the supermassive black holes at the centers of galaxies have powerful jets blasting from their poles, and others have weak jets, but many don't have jets at all.
Some black holes are in a bigger hurry than others, hence bigger jets. While the ones that don't have jets are more concerned about the environment and galactic warming so they use public transportation.
How is it possible? (Score:1)
Is the spin of a black hole determined by the event that created it? For example the spin of the star that collapsed? And doesn't an opposing accretion disk create a lot of drag on the spin of the black hole?
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The Electric Universe (Score:1, Troll)
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Huh? (Score:1, Offtopic)
Well in Oprah’s case it’s because of her show. Dunno about the others though. ;)
One theory... (Score:2)
... is that the black hole is composed purely of dark matter, and the intense gravity strips the dark matter (ie. mass/gravitational attraction) from the charged particles (protons/electrons), which then repel each other as jets, while the dark matter just consolidates into the black hole.
Is it really surprising? (Score:2)
well (Score:1)
Why the hole gotta be black? (Score:1)
County commissioner laments the color choice for "black" holes:
http://www.youtube.com/watch?v=YAw5D1-8IrQ#t=39s [youtube.com] (sorry, bad audio)
These Guys is why... (Score:2)
http://billwardwriter.com/wp-content/uploads/2010/02/blackhole-vincent-bob.JPG [billwardwriter.com]
The Theory of Black Holes Leading to New Universes (Score:1)
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You must be in the NAACP:
http://abclocal.go.com/kabc/story?section=news/local/los_angeles&id=7475737 [go.com] :(