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Black Hole Particle Jets Explained

Posted by Soulskill on Thu Apr 24, 2008 02:01 PM
from the never-turn-your-back-on-an-accretion-disk dept.
Space Science
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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Submission: Black hole jet streams explained by Screaming Cactus (1230848)
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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.

      • 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!"

      • Re:Hawking Radiation (Score:5, Insightful)

        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.
      • 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.
        • Large ones will start to evaporate... in a few trillion years once the CMB cools down enough.

            • 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).

        • 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.

              • 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,

        • 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.

  • The scatological aspects of astronomy. (Score:5, Funny)

    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.

    • Re:The scatological aspects of astronomy. (Score:4, Informative)

      by oodaloop (1229816) on Thursday April 24 2008, @02:26PM (#23187930) Homepage

      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.

      • I am french that is not informative (Score:5, Informative)

        by aepervius (535155) on Thursday April 24 2008, @11:21PM (#23194028)
        Black hole translate to "trou noir", which is as funny (or unfunny) as "black hole" is in english. I don't ever recall an astrophysicists in France which was annoyed, or amused. I would REALLY like to see a reference to this.And to the moderator, such an assertion would require at least a lnik or reference to be modded informative +5. Right now at best it is only +5 funny.
    • 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.

  • This is how science works (Score:5, Insightful)

    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.

    • 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?

    • 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?

    • 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 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

      • 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

      • Re: (Score:2, Informative)

        by Kenja (541830)

        Well, except global warming, obviously. That just gets accepted as is, since anyone who suggests otherwise is probably an oil company shill.
        Um, we have decades of direct testing and thousands of years of indirect data supporting global warming. It has been and continues be heavily tested.
        • You're making the very common mistake of using sloppy terminology. "Global warming" is not necessarily the same thing as "anthropogenic (human-caused) global warming". The former is directly observable; the latter is not. We can build computer models that predict how human activity causes (or at least contributes to) the warming; and, if warming continues over time, the chance that it is just due to natural variation goes down with every new year the trend holds. But just observing that the climate has warm

      • Re: (Score:2, Insightful)

        by jav1231 (539129)

        Well, except global warming, obviously. That just gets accepted as is, since anyone who suggests otherwise is probably an oil company shill.
        It's called "climate change" now. That way if the current trend of lower temps continues and we go into another mini ice age (as some are predicting) they're still right!

        BRILLIANT!

        • Im tenatively convinced about global warming for the following reason: acidic ocean water.

          As anybody in chemistry knows, dissolving CO2 in water results in H2CO3, an acid. Only 2 major variables result in this, and that is pressure and amount. Since our pressure is roughly constant (28mmHg-32mmHg), that leaves the amount of CO2 to be rising.

          Now, how can we look at prior trends of CO2 affecting the oceans? Simple. H2CO3 is an acid, and tends to leach calcium from single-celled creatures in the sea water. Now
          • You provided evidence for an increase in CO2, not evidence for a prolonged warming trend BASED on an increase in CO2. It's the latter issue that is causing concern, and the question is whether it's warranted.

        • Re:This is how science works (Score:4, Insightful)

          by macemoneta (154740) on Thursday April 24 2008, @02:54PM (#23188366)

          It's called "climate change" now. That way if the current trend of lower temps continues and we go into another mini ice age (as some are predicting) they're still right!

          It's called "climate change" now because people had problems understanding the concept of global warming; they concentrated on the terminology instead of understanding the process.

          Energy is being added to the Earth's outer layer, including the atmosphere. This additional energy is like turning on a blender - everything is going to get mixed up. Places where it was cold may turn warm. Places where it was warm may become cold. Deserts will form where there was arable land. Dry places may get wetter. The ice caps act as a thermal buffer (like the ice cubes in a drink), and the additional energy is causing them to melt. This in turn raises sea levels.

          Things get complicated because of the political boundaries; people can't just move to where things are becoming nicer. If the farm land in the U.S. turns to a dust bowl for example, we can't just pick up 300M people and move to another country - just as the U.S. doesn't open its borders to tens of millions dying of thirst and starvation in other countries.

          A secondary complication is the delicate balance between airborne particulates and greenhouse gases. Reducing pollution levels reduces both, but not at the same rate. As the two have opposing impacts, and tend to be politically controlled by local goverments, it's and extra monkey wrench in the calculations.

          In this context, the term "climate change" is easier for people to grasp. It doesn't change what is happening.

        • Re: (Score:3, Interesting)

          by Medievalist (16032)

          Well, except global warming, obviously. That just gets accepted as is, since anyone who suggests otherwise is probably an oil company shill.

          It's called "climate change" now. That way if the current trend of lower temps continues and we go into another mini ice age (as some are predicting) they're still right!

          Look, I hate to interrupt your meta-scoffing... but...

          I personally sat through a lecture nearly 20 years ago that was given at the Stroud Water Research Center by the guy who discovered "global warming". I remember he was introduced by Dr. Ruth Patrick of the Academy of Natural Sciences in Philadelphia. AT THAT TIME, he said the worst mistake he'd ever made in his career was allowing the name "global warming" to get attached to what he was studying. He said that the global average warming trend was an i

      • That just gets accepted as is,
        Noooo... you propose a theory, then test it against all the past data that has been collected. You may have noticed how the models have changed quite a bit in the last 30 years as the models improve and more data is collected.
      • Evolution is a good explanation of "accepted" evidence. One cannot test it, therefore it isn't science.


        Right. Because the fossil record of both horses and humans do not show examples of intermediate changes from non-horses and non-humans to todays creatures.

        And I suppose astrology is a science because it's so well "tested".

      • No you'll be flamed for demonstrating your ignorance.
        Those dinosaurs you see at your local museum are just the tip of the iceberg. At this point millions, maybe even hundreds of millions of fossils have been found.
        Hundreds of thousands of bones/fossils have been found at single dig sites.

        The dots have been connected, by looking at the fossils you can actually watch some of the more complete species on record morph over time, sometimes to drastically different shapes
        But you won't be satisfied until yo
      • Do you think that they made a black hole in the lab to "test" these theories?

        Tracing the fossil record, and mapping historical changes in various genomes would be enough solid evidence for anyone who didn't have an irrational bias.

        Like it or not, evolution through natural selection is a robust, predictive theory. So far we've only successfully applied it to things that have extremely fast reproductive cycles (e.g bacteria) but, again, that's good evidence.

        Until you can actually produce a good argument based

      • When you can take a bacteria, and make a mouse using only "natural selection", then I'll accept that you've "tested" evolution.

        How do you know the Earth isn't really a big giant Petri dish that someone is using to test evolution right now?

      • Evolution has been tested. There are organisms that have a short life span (e.g. fruit flys). You don't test a theory to prove it, you test a theory to disprove it.

        Evolution is testable, has been tested, and so far has not been disproven. If it is disproven, then another theory will take its place.
      • The overwhelming evidence for proving natural selection is the fossil record. To test evolution you look at the data from the fossil record to prove or disprove your hypothesis. Not one fossil has disproven natural selection so far. Given how many millions of fossils have been found so far, I'd say that theory is pretty well tested.

      • Re: (Score:3, Insightful)

        by steelfood (895457)
        Wow, and this junk got modded insightful?

        Here's something that you can do and in fact has been done over a timeframe of the past 50 years:

        Take a large pool of bacteria, start killing them off with antibiotics, rinse, and repeat.

        Now, the bacteria is your organism, the antibiotics the selective pressure. Natural selection dictates that eventually through random mutations, there will be bacteria that will no longer be susceptible to antibiotics.

        Lo and behold, this has exactly happened. The overuse of common an

        • I do not understand the irrational knee-jerk reation to evolution that "Good Ol' Righteous God Fearing Folk" have.

          I'm agnostic, but let me take a stab at an answer to your question...

          I think that bot Christians and Evolutionists have a spectrum of positions within their two camps; some are compatible, some aren't:

          • Some Christians believe that the book of Genesis was meant to be understood literally rather than metaphorically or poetically. So to them, all Evolutionist viewpoints are incompatible with

  • Good science writing (Score:5, Insightful)

    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.

  • Particles coming out of blackholes... (Score:3, Funny)

    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?
  • 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

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