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Space Science

Black Hole Particle Jets Explained 201

Posted by Soulskill
from the never-turn-your-back-on-an-accretion-disk dept.
Screaming Cactus writes "A team of researchers led by Boston University's Alan Marscher have apparently worked out the physics behind the particle streams emanating from many black holes. According to the researchers, 'twisted, coiled magnetic fields are propelling the material outward.' By watching an 'unprecedented view' of a black hole in the process of expelling mass, they were able to confirm their theory, predicting where and when bursts of energy would be detected."
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Black Hole Particle Jets Explained

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  • So this is separate from Hawking Radiation? Black holes emit two kinds of energy?
    • Re:Hawking Radiation (Score:5, Informative)

      by PhuCknuT (1703) on Thursday April 24, 2008 @02:14PM (#23187774) Homepage
      Yes, this is completely different, but it's not exactly the black hole emitting anything. The jets are from material that hasn't fallen into the black hole yet, being accelerated along the axis of rotation by the twisted magnetic fields outside the black hole.

      • by techpawn (969834)

        The jets are from material that hasn't fallen into the black hole yet
        So those sci-fi movies with "we'll sling shot around the sun" should really try "We'll sling shot around that black hole!"
      • by Walt Dismal (534799) on Friday April 25, 2008 @03:49AM (#23195290)
        I've always wondered whether magnetic fields inside a black hole are restricted to being within the internal boundary of the black hole, but not able to penetrate outside it? Does the event horizon also apply to them? Does the boundary established by the hole's gravitational field prevent a magnetic field from emerging? That would imply gravity can trump magnetism. I guess that makes sense if gravity warps space, and magnetism has to propagate through space, so if space is distorted the magnetic field lines are too. So does this mean one could somehow bottle up enormous magnetic fields within a gravity-compressed space? Does this operate in suns to contain their reactions? And why do my friends from Tau Ceti always look at me like I was crazy when I ask them this? Just because I'm human doesn't mean they have to treat me like a galactic retard. Although that explains the Slinky they gave me, claiming it was advanced alien technology.
    • Re:Hawking Radiation (Score:5, Informative)

      by ekstrom (941853) on Thursday April 24, 2008 @02:17PM (#23187818)
      This is radiation from the accretion disk, which both supplies the material and twists up the fields which then accelerate the material. It's not from the hole itself. Of course it is all powered by the hole's gravitational field.
      • by RobinH (124750)
        So is the energy (to accelerate the particles in the jets) coming from the loss of potential energy of matter that is falling into the black hole, or is the energy from the black hole itself?
    • Re:Hawking Radiation (Score:4, Informative)

      by Jugalator (259273) on Thursday April 24, 2008 @02:17PM (#23187824) Journal
      These particle jets aren't emitted from the actual "depths" of a black hole, but as the article says, ejected due to twisted magnetic fields perpendicular to its accretion disk. Once you get closer, space bends even the magnetic fields inwards, and everything else. And what goes that far is later emitted as Hawking radiation, the only form of energy theorized to be emitted from a black hole, in time believed to "evaporate" the black hole itself.
      • Re:Hawking Radiation (Score:5, Informative)

        by evanbd (210358) on Thursday April 24, 2008 @02:31PM (#23188002)
        Well, large black holes don't evaporate -- even the cosmic background radiation is enough to add more mass than they lose to Hawking radiation. The CMB is at ~2.7K, and a 1 solar mass black hole has a temperature of 60nK from the Hawking radiation.
        • by PhuCknuT (1703)
          Large ones will start to evaporate... in a few trillion years once the CMB cools down enough.
          • by Jugalator (259273)
            Yes, I probably should have added a 10^100 years or so disclaimer to "in time". Hehe. But I actually didn't realize that was because of the CMB, never considered that. I just thought they radiated slow enough. So I guess I learnt something there too, hehe.
            • Re: (Score:3, Informative)

              by PhuCknuT (1703)
              It's both, they radiate very slow and the CMB will be warmer than them for a long time. I just looked it up, a stellar mass black hole will take 10^67 years to evaporate. I was way off when I said trillions. :)

              The cool thing is, as they get smaller, they radiate faster. So they get smaller and hotter exponentially, and finally die (in theory...) in a massive burst of gamma rays. In the last second, they emit as much energy as a 5000000 megaton nuke. Would be a hell of a show (from a safe distance).
              • do you think that this gamma ray burst you speak of in the last few seconds of the SM black hole's life might have something to do with 'restartng' our universe once everything gets consumed by black holes?

                IANAP, but i have been reading up on the ultimate fate of the universe and it seems like the going theory is "with a whisper"

                correct me if i'm wrong, but once the universe is completely 'flat' in a google years, current ideas say that only another brane collision could start another big bang
        • Well, large black holes don't evaporate -- even the cosmic background radiation is enough to add more mass than they lose to Hawking radiation. The CMB is at ~2.7K, and a 1 solar mass black hole has a temperature of 60nK from the Hawking radiation.

          Yet. The operational word is "yet". As the Universe ages, the cosmic background temperature will decrease until the point that even a very large black hole will radiate.

        • My understanding of hawking radiation is that a particle/anti-particle pair is created near the event horizon. One particle falls in and the other falls out. It's the ones that fall out that are called hawking radiation, and the particles falling in contribute to the black hole's demise.

          The question that arises in my mind is this. Presumably there is a 50/50 chance that it's the particle that's being emitted, and the anti-particle falling into the hole. The other 50% of the time it's the antiparticle
          • by evanbd (210358)
            Antiparticles have positive mass, but opposite charge (and in the case of things like proton vs antiproton, the internal quarks are changed to antiquarks, etc). So yes, the black hole does lose mass, even though half of the radiation is antimatter.
            • Antiparticles have positive mass, but opposite charge (and in the case of things like proton vs antiproton, the internal quarks are changed to antiquarks, etc). So yes, the black hole does lose mass, even though half of the radiation is antimatter.

              That makes no sense. If both the particle and antiparticle have the same positive mass, then the black hole will increase in mass, not decrease.
              • Re: (Score:3, Informative)

                by evanbd (210358)

                There's a black hole. Quantum vacuum fluctuations create a particle-antiparticle pair near it, both with positive mass. One falls in, the other escapes. Thanks to quantum weirdnesses, the mass for the escaping one gets stolen from the black hole. Half the time it will be the antiparticle escaping, and half the time the particle. (Overall, though, they'll mostly do the same thing and both fall toward it or away from it, and annihilate each other with no net effect. But on the rare occasion when they ge

              • Re: (Score:3, Interesting)

                by teebob21 (947095)
                Hawking radiation particles don't come from *inside* the black hole; that's impossible. Instead they are the "virtual particle" pairs that are constantly created (and almost always immediately destroyed) from vacuum fluctuations [wikipedia.org] of the fabric of space time, specifically those pairs pop into existence straddling the infinitely thin line that is the event horizon. Due to gravitational acceleration, these particles become real due to the Unruh effect [wikipedia.org]. If the antimatter particle, say an antiproton, is captured,
          • by ChatHuant (801522)
            My understanding of hawking radiation is that a particle/anti-particle pair is created near the event horizon. One particle falls in and the other falls out. It's the ones that fall out that are called hawking radiation, and the particles falling in contribute to the black hole's demise.

            The question that arises in my mind is this. Presumably there is a 50/50 chance that it's the particle that's being emitted, and the anti-particle falling into the hole. The other 50% of the time it's the antiparticle tha
            • by evanbd (210358)
              The relevant ones aren't the particles that fall in, but the ones that leave. Externally, they appear to have been created from nothing; but the mass has to come from somewhere, and it comes from the black hole. The details of why are not something I fully understand (IANAP either).
      • by IorDMUX (870522)
        So, I understand (in a manner of speaking) the whole material ejection process, so to speak. I was wondering if someone could clear up an issue for me, though... Why do accretion disks form in the first place? I mean, why a single disk rather than a sphere of material being drawn in to the essentially "spherical" black hole? Why is one plane favored above all others? Is it because the black hole itself is rotating?
        • Re: (Score:3, Informative)

          by qeveren (318805)
          If you have a spherical collection of particles randomly orbiting an object, collisions between particles tend to average out their angular momentum, eventually concentrating them into a thin disk. The oblateness of the rotating primary about which they orbit tends to force that ring into alignment with the primary's equator.
    • I call it a Hawking Hole
  • by Kenja (541830) on Thursday April 24, 2008 @02:10PM (#23187720)

    an 'unprecedented view' of a black hole in the process of expelling mass


    Ok, so its juvenile and stupid. But it still made me laugh.
    • by oodaloop (1229816) on Thursday April 24, 2008 @02:26PM (#23187930)

      Ok, so its juvenile and stupid.
      Not really. You may not be aware, but one of the reasons the term Black Hole stuck around was to annoy French astrophysicists (the term translates to a bodily orafice in French). The question was later posed (by Wheeler, I believe) as to whether black holes have 'hair', meaning do they give off observable radiation or other phenomena, much to the chagrin of his French counterparts. The question was posed, FWIU, mostly just so American physicists could snicker while French physicists had to talk about black holes and hair in public conferences. And it turns out that yes, black holes do in fact have hair.

      Now we have black holes expelling mass. I'm sure you're not the only one finding this humorous.
    • bh: heh heh... he said expelling mass ... uhhhh heh heh heh...
    • French speaking nations tend to dislike the literal translation of "black hole" into their language... It doesn't translate well.
      • I have some lectures on black holes in mp3, and listening to the Japanese speakers talk about "brack hos" gets me going every time.
  • by smooth wombat (796938) on Thursday April 24, 2008 @02:10PM (#23187730) Homepage Journal
    'By watching an 'unprecedented view' of a black hole in the process of expelling mass, they were able to confirm their theory, predicting where and when bursts of energy would be detected."


    Note to all ID supporters, this is how real science works. Propose a theory which can be tested, then go about trying to disprove the theory.

    Now go ahead, flame me. My karma can take it.

    • by Kenja (541830)
      Actually, "real science" goes like this.

      Propose a theory to explain an observable phenomenon. Then attempt to disprove it. If it stands up to scrutiny it stands until disproved or a better theory comes along. The base theory itself does not need to be tested, in fact by definition it can not be proven, only disproved.
      • I wonder if in the future we will have to separate evolution from intelligent design (of the human kind).

        Natural evolution vs forced genetic selection?
      • Actually, it can't be disproved, either, in the sense that it can always be tweaked this way and that to accommodate experimental results. Theories fall into and out of favor according to whether or not the majority of scientists in a given field prefer them to the alternatives.
    • Propose a theory which can be tested, then go about trying to disprove the theory.

      That's assuming that all theories can be tested. Or, to put it another way: If you can't test it, is it a theory? According to Merriam-Webster, [merriam-webster.com] yes. Inference points towards your disputing that. Is this the problem in a nutshell?

      • by qeveren (318805)
        The meaning of the word 'theory' differs wildly between the colloquial usage and the much more rigid definition used by science.
    • by ArcherB (796902)

      Note to all ID supporters, this is how real science works. Propose a theory which can be tested, then go about trying to disprove the theory.

      Or you can present a theory and then set about trying to PROVE it. Many times, it leads to other theories. Take, for example this [wikipedia.org] story:

      Premise: God created the Universe, as stated in the Old Testament.
      Theory: The Universe had a beginning.
      Test: Use Einstein's formula's to track time back until you find a beginning.
      New Theory: Big Bang.

      Note: I believe in ID. I just believe that in order to reach the "Design", evolution was used. Please don't assume that religion is a rejection of science. Many rel

      • Note: I believe in ID. I just believe that in order to reach the "Design", evolution was used.

        1) Surely you mean "is being used", not "was used". Evolution hasn't stopped, not can be expected to ever stop (evolving to not evolve would be mal-adaptive). Conceivably there's an attractor that life will eventually circle, but we're not looping yet!

        2) Even if evolution did, unexpectedly, arrive at some final "Design" (even if a dynamic rather than fixed one), we're not there yet, nor is there much chance that an
        • by ArcherB (796902)

          Note: I believe in ID. I just believe that in order to reach the "Design", evolution was used.

          1) Surely you mean "is being used", not "was used". Evolution hasn't stopped, not can be expected to ever stop (evolving to not evolve would be mal-adaptive). Conceivably there's an attractor that life will eventually circle, but we're not looping yet!

          I stand corrected.

          2) Even if evolution did, unexpectedly, arrive at some final "Design" (even if a dynamic rather than fixed one), we're not there yet, nor is there much chance that anything resembing man or anything described in the Bible will be a part of it. Time will take care of that. In a few tens/hundreds of millions of years Homo Sapiens will be nothing but a random species far back on the evolutionary tree - no more priviliged than any other point in our own current evolutionary history. Most branches of the evolutionary tree are dead ends, and only a few keep growing... there's no guarantee that our branch (or maybe mammals as a whole) will not eventually be a dead end, and it may well be that in 100,000,000 or so years time there's no species left with the intelligence to even ponder how insignificant our own species proved to be.

          I believe that the final design was man and the ecosystem to support us. As for man finally evolving to something else, the Bible states that the world will end long before that happens. I guess we'll find out in 100,000,000 years or so! :-)

          • I believe that the final design was man and the ecosystem to support us. As for man finally evolving to something else, the Bible states that the world will end long before that happens.

            Why pick and choose? If you believe we're descended from apes then you've already thrown out one chunk of the Bible as well as any notion of us being anything other than animals... So why do you choose to believe the Bible on the end game if you reject it on the beginning? Seems kinda arbitrary !

            • by ArcherB (796902)

              I believe that the final design was man and the ecosystem to support us. As for man finally evolving to something else, the Bible states that the world will end long before that happens.

              Why pick and choose? If you believe we're descended from apes then you've already thrown out one chunk of the Bible as well as any notion of us being anything other than animals... So why do you choose to believe the Bible on the end game if you reject it on the beginning? Seems kinda arbitrary !

              Evolution doesn't make the claim that man is a descendant of apes. Evolution claims that man and apes have a common ancestor, but then again, EVERY species has a common ancestor!

      • Note: I believe in ID. I just believe that in order to reach the "Design", evolution was used. Please don't assume that religion is a rejection of science. Many religious scientists use science to find out HOW God works.

        Ten-to-one odds you get flamed by a devout agnostic...

        What's funny is that many agnostics/atheists are convinced that "belief" and "science" are incompatible, and will try to ridicule anyone that suggests differently.

        "Faith", indeed.

      • by plague3106 (71849)
        Instead of yelling at those of us that are sick of most IDers saying evolution can't exist, why don't you yell at the nutjobs that also believe in ID but don't believe evolution.
        • by ArcherB (796902)

          Instead of yelling at those of us that are sick of most IDers saying evolution can't exist, why don't you yell at the nutjobs that also believe in ID but don't believe evolution.

          Because *MOST* ID'ers (Christians, Jews, Muslims and whatever else) don't have a problem with evolution.

          Besides, I haven't found any of those "nutjobs" here on slashdot. Those of you that are "sick of most IDers saying evolution can't exist" and post it here on slash are just yelling at the choir, so to speak.

          Outside of slashdot, in many of the churches I've attended, I haven't met anyone who doesn't believe in evolution in some shape or form. I even read a Creationist book that claimed that God put anim

    • Note to all ID supporters, this is how real science works. Propose a theory which can be tested, then go about trying to disprove the theory.

      Note to all anti-ID people, not all propositions can be tested by scientists. Especially alleged miracles, which are by definition one-off phenomena caused by an external agent that is itself inscrutable to human-devised experimentation.

      I too would offer to be flamed, but I think that's pretty unnecessary considering the position I just advanced. The down-modding

      • by steelfood (895457)
        Note to all anti-ID people, not all propositions can be tested by scientists. Especially alleged miracles, which are by definition one-off phenomena caused by an external agent that is itself inscrutable to human-devised experimentation.

        And that's what makes it irrelevant to science, and more importantly, not science.

        And if you're saying that miracles can be used to show ID is viable, then I think you'd agree that it shouldn't be taught with science in a science class. Maybe it should be taught in a class c
        • And that's what makes it irrelevant to science, and more importantly, not science.

          And if you're saying that miracles can be used to show ID is viable, then I think you'd agree that it shouldn't be taught with science in a science class. Maybe it should be taught in a class called, oh, I don't know, theology perhaps?

          Sure, I'm ok with that. I have no problem with a science class teaching that there's a good case for evolution. But we should remember that there are at least two versions of ID: (a) no e

      • by mcmonkey (96054)

        Note to all anti-ID people, not all propositions can be tested by scientists.

        Don't you mean, note to all pro-ID people? The argument against ID and specifically the argument for keeping ID out of science class when the discussion turns to evolution is exactly as you state it--not all propositions can be tested by scientists.

        ID does not belong in science class not because it's not true. It does not belong because it is not science.

        Science is not a collection of facts, it is a method of discovering

        • So if you agree ID cannot be tested and therefor is not science, then surely you agree it does not belong in a science class. That is all the anti-ID folks are saying.

          That sounds reasonable. On the other hand, I don't think students should be hermetically shielded from the anti-evolution arguments that ID people make. I've seem some ID people make non-theological arguments against certain aspects of evolutionary theory. If you shut out these arguments just because they're made be people who also make t

          • ID is testable. It simply assumes a creator and then requires you to hypothesize about the will of your creator. For example, you could hypothesize that your creator would design the earth's environment to be in a state of semi-stable equilibrium so that life can exist. This is a scientifically testable hypothesis.

            I think that people get hung up on the fact that you can't disprove the existence you your creator using ID (since your interpretation of your creators purpose might be wrong, or your creators
  • by ekstrom (941853) on Thursday April 24, 2008 @02:13PM (#23187756)
    This is a good article. It was complete enough to satisfy the casual interest of this old physicist who once worked for awhile as an astronomer, explained all of its terms in ways accessible to a more general public, but was never tedious about it. We need more science writing of that quality. Also good work, it would seem. Rarely do you get a chance to check astrophysical theory in such detail against observations.
  • by Whatanut (203397) on Thursday April 24, 2008 @02:19PM (#23187852)
    That's what's left of the poor alien souls that attempted to use a pair of them for travel...
  • Where does the magnetic field perpendicular to the accretion disk come from? Does the material in the accretion disk carry a net charge?
  • Old hat (Score:2, Informative)

    by jessica_alba (1234100)
    From http://en.wikipedia.org/wiki/Birkeland_current [wikipedia.org] "A Birkeland current generally refers to any electric current in a space plasma, but more specifically when charged particles in the current follow magnetic field lines (hence, Birkeland currents are also known as field-aligned currents). They are caused by the movement of a plasma perpendicular to a magnetic field. Birkeland currents often show filamentary, or twisted "rope-like" magnetic structure."

    I wonder when they will discover that these "super ma
  • This should be causing the black hole to lose energy then, because you can't accelerate matter to high speeds without putting energy into it, and that energy has to come from somewhere.

    Also TFA refers to this as a "tremendous particle accelerators". Is it busy creating Higgs bosons then?

    • by Lijemo (740145)

      This should be causing the black hole to lose energy then, because you can't accelerate matter to high speeds without putting energy into it, and that energy has to come from somewhere.

      The black hole is losing energy because of this. Just like you lose energy by absent-mindedly tapping your fingers on a table-top. But in both cases, it's not enough energy for either you or the black hole to notice unless it's kept up for eons.

      Also TFA refers to this as a "tremendous particle accelerators". Is it busy creating Higgs bosons then?

      That's the $25,000 question, isn't it? Particle physicists would LOVE to be able to set up their detectors alongside this thing and find out.

    • by adisakp (705706)
      This should be causing the black hole to lose energy then, because you can't accelerate matter to high speeds without putting energy into it, and that energy has to come from somewhere.

      I'm a bit distressed that a slashdotter like yourself has never heard of gravity. Did you ever take a physics class in your life?
  • Simple, cause it sux.

The reason that every major university maintains a department of mathematics is that it's cheaper than institutionalizing all those people.

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