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Galactic Pancake Mystery Solved 117

Posted by CowboyNeal from the galactic-syrup-lay-undiscovered dept.
mOoZik writes "According to the BBC, Astronomers have figured out why a series of small galaxies surrounding the Milky Way are distributed around it in the shape of a pancake. Theorists believed that the eleven dwarf galaxy companions should have a diffuse, spherical arrangement, but a University of Durham team used a supercomputer to show how the galaxies could take the pancake form without challenging cosmological theory."
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Galactic Pancake Mystery Solved More

Galactic Pancake Mystery Solved

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  • Next on Pancake Galactica (Score:4, Funny)

    by Anonymous Coward on Saturday April 09, 2005 @11:39AM (#12187314)
    The evil Egglons attack, wiping out most of breakfast.

  • A pancake... (Score:5, Funny)

    by Poromenos1 ( 830658 ) on Saturday April 09, 2005 @11:39AM (#12187318) Homepage
    Aha, now all that remains is to find a galaxy shaped like a bottle of maple syrup!

  • In depth ... (Score:5, Insightful)

    by foobsr ( 693224 ) on Saturday April 09, 2005 @11:39AM (#12187322) Homepage Journal
    ... and more credit ... (and to enhance discussion :) ...

    Full article [lanl.gov]

    The Distribution of Satellite Galaxies: The Great Pancake

    Noam I Libeskind, Carlos S Frenk, Shaun Cole, John C Helly, Adrian Jenkins, Julio F Navarro and Chris Power

    ABSTRACT
    The 11 known satellite galaxies within 250 kpc of the Milky Way lie close to a great circle on the sky. We use high resolution N-body simulations of galactic dark matter halos to test if this remarkable property can be understood within the context of the cold dark matter cosmology. We construct halo merger trees from the simulations and use a semianalytic model to follow the formation of satellite galaxies. We find that in all 6 of our simulations, the 11 brightest satellites are indeed distributed along thin, disk-like structures analogous to that traced by the Milky Way's satellites. This is in sharp contrast to the overall distributions of dark matter in the halo and of subhalos within it which, although triaxial, are not highly aspherical. We find that the spatial distribution of satellites is significantly different from that of the most massive subhalos but is similar to that of the subset of subhalos that had the most massive progenitors at earlier times. The elongated disk-like structure delineated by the satellites has its long axis aligned with the major axis of the dark matter halo. We interpret our results as reflecting the preferential infall of satellites along the spines of a few filaments of the cosmic web.

    CC.

    • Re:In depth ... (Score:4, Insightful)

      by Martin Blank ( 154261 ) on Saturday April 09, 2005 @12:01PM (#12187444) Homepage Journal
      There still isn't anything about why it happens. OK, so the simulation repeats history. It would be nice if at least some explanation were provided for it. Gravity? Dark energy? Stellar cheese?

      • Re:In depth ... (Score:2, Interesting)

        by foobsr ( 693224 )
        Asking why is metaphysical in (at) the end :)

        Anyway, there they have some more readable info [phys.uvic.ca]

        CC.

      • Re:In depth ... (Score:4, Insightful)

        by stygianguest ( 828258 ) on Saturday April 09, 2005 @01:25PM (#12187895)
        From what they understand they just showed that the available theories (well, the ones they chose to use) already give an explanation of the current situation.

      • Re:In depth ... (Score:1, Informative)

        by Anonymous Coward
        How about the forces they included in the simulation? Surely they work as an explanation one level back. It gets harder if you want to know why the forces act like they do.
      • Galaxy formation is largly determined by large globs of what scientists refer to as "Dark Butter" deep out in space.

      • The key to this idea is that, given a particular set of initial conditions for the perturbations of density after the Big Bang, matter becomes concentrated in long, thin, filamentary structures. When those structures collapse under the influence of gravity, the result is group of galaxies -- in this, one big one and several small ones -- stretched out along the axis of the early filament(s). So, rather than being distributed all around the big galaxy in a spherical cloud, the little galaxies are arranged

    • You know, however, that it's all just a hoax to make pancakes tax deductable...

  • So therefore... (Score:5, Funny)

    by Z0mb1eman ( 629653 ) on Saturday April 09, 2005 @11:45AM (#12187357) Homepage
    It's bunnies all the way down?

  • Short answer (Score:5, Funny)

    by Anonymous Coward on Saturday April 09, 2005 @11:46AM (#12187363)
    Our local cluster is a franchise of IHOP (intergalactic house of pancakes).

  • In other news.... (Score:4, Funny)

    by spiderworm ( 830684 ) on Saturday April 09, 2005 @11:47AM (#12187369)
    ... researchers are still working on the mystery of the cosmic sausage and eggs, as well as new puzzling information that seems to indicate the presence of a Great White Handkerchief... or maybe it's a napkin?

  • Without challenging cosmological theory (Score:4, Funny)

    by Anonymous Coward on Saturday April 09, 2005 @11:49AM (#12187375)
    Dark Syrup explains galactic pancake mystery.

  • Remind you of anything? (Score:4, Interesting)

    by Daxx_61 ( 828017 ) on Saturday April 09, 2005 @11:51AM (#12187387) Homepage
    This sounds a little like planetary formation. What if these 'halos' were really rings, due to some sort of spin in the original setup? Do they have to be a 3-dimensional halo? I am not an astronomer, but it sounds reasonable to me - could someone please explain this?

    • Re:Remind you of anything? (Score:1, Funny)

      by Anonymous Coward
      The halos are, in fact, rings left by an ancient race of beings who were far more technologically advanced. There appear to be seven in total, although one seems to have been destroyed recently...
    • This sounds a little like planetary formation. What if these 'halos' were really rings, due to some sort of spin in the original setup? Do they have to be a 3-dimensional halo?

      IANAA, but it seems reasonable to me that a 3-D rotating ellipsoid *would* collapse (due to gravitation) along its smallest axis -- the one running "vertically" through the center of the galactic mass -- thus "flattening out" in the other two dimensions.

  • Before anyone thinks of putting dark matter syrup (Score:3, Funny)

    by Anonymous Coward on Saturday April 09, 2005 @12:01PM (#12187450)
    ...on this pancake, Smucker's already has a patent on it.

  • Well... (Score:2, Funny)

    by rob_squared ( 821479 )
    ...there *are* certain galaxies that look like oranges. http://www.eso.org/outreach/press-rel/pr-2003/imag es/Phot32/phot-32a-03-normal.jpg [eso.org]

  • Silly scienticians! (Score:2, Interesting)

    by Flamekebab ( 873945 )
    without challenging cosmological theory
    Isn't it supposed to be about challenging current theories?
    • Isn't it supposed to be about challenging current theories?

      No, it's supposed to be about parsimony. If you find an explanation of a phenomena that fits with current theories, that's favorable to throwing out a bunch of current theories just to explain your phenomena.

      It's called "simpler." We like simpler.

  • A Quick Question (Score:3, Interesting)

    by MankyD ( 567984 ) on Saturday April 09, 2005 @12:19PM (#12187525) Homepage
    I've got a slightly more than average knowledge base on cosmology (though maybe not more than your average slashdotter). I've read a few books, but one thing I've never cleared up: Why do galaxies form in flat spirals and pancaks, and not in gravitationally stable spheres? Is there a simple reason I'm missing?
    • Mod me down - I just remembered why. I'm an idiot.

    • Re:A Quick Question (Score:5, Informative)

      by imsabbel ( 611519 ) on Saturday April 09, 2005 @12:39PM (#12187619)
      Angular Momentum

      If you have a total angular momentum of 0, you get an eliptical galaxy. All stars have totally random orbital orientations around the center, so it gives an elipsoid. it COULD be a sphere (but what do you mean with gravitational stable? all galaxies are dynamic), but the chances are rather slim).
      If there is a angular momentum, it will create a disc simply because thats a lower energy state with the same angular momentum compared to a sphere.

      • Re:A Quick Question (Score:3, Interesting)

        by Pedrito ( 94783 )
        I'll grant that I'm no a math whiz, so I don't know the mathematics involved, but the reasons seem so obvious as to make me wonder how this could possibly challenge "cosmological theory." Most galaxies are pancake shaped. Most solar systems are pancake shaped. As you mentioned, nothing is really "gravitationally stable." I mean, if there's any movement at all, things are going to coalesce into a pancake shape eventually, unless all the movement is completely canceled out by opposite forces/movement, which i

      • Re:A Quick Question (Score:5, Interesting)

        by Bastian ( 66383 ) on Saturday April 09, 2005 @01:20PM (#12187860)
        So what you're saying is that you have to have the matter in the galaxy orbit (more or less) around a common axis, like in our solar system.

        What would cause this to happen, instead of there being a bunch of randomly-oriented orbits?

        (I suppose I am making the critical assumption that the distribution of matter immediately after the big bang was uniform, and I'm sure any cosmologist would be happy to smack me down over that, but I'll ask anyway.)

        • Re:A Quick Question (Score:1, Insightful)

          by Anonymous Coward
          Even if you have a bunch of uniformly randomly-oriented orbits, there is always at least a little angular momentum in some direction; you never get perfect statistical cancellation to zero. This angular momentum is conserved, and as the cloud of matter collapses gravitationally, the rotational effect is amplified (like a spinning figure skater pulling in his/her arms).

        • Re:A Quick Question (Score:2, Interesting)

          by ph43drus ( 12754 )
          IAAP (I am a physicist), and the gravitationally stable spheres is a problem. That's what this study was looking at.

          The bright, visible, normal matter forms into a disk in every galaxy we see. This cannot be explained with Newtonian gravity (or Einsteinian, for that matter). You see, when you just stick the normal matter in a simulation to check the evolution of a galaxy, it doesn't stay in the disk shape. To get the simulations to work (meaning, predict disk galaxies), you have to put a spherical halo

          • Re:A Quick Question (Score:3, Interesting)

            by Bastian ( 66383 )
            I am actually glad to hear that. . . I don't know enough about current physics to really make any sort of valid judgement on the theory. (I frequently get the feeling that I don't even understand the basic ideas behind relativity very well.) But the idea of dark matter always seemed to me to be rather fishy, sort of like the old crystal spheres that held the planets aloft.
            I mean, they're both explanations for physical phenomena that were unexplainable under the model for how the universe worked at the tim

          • Re:A Quick Question (Score:2, Interesting)

            by Anonymous Coward
            I am a physicist too, and I suggest you review some astrophysics.

            Dark matter is more than a "cop out". If dark matter only explained one thing, it might be a cop-out, but it simultaneously explains observations in cosmology, observations of galactic rotation curves, and large-scale structure formation -- all independent phenomena. This is a nontrivial accomplishment.

            It is also not true that no particle theorists have come up with anything which could be dark matter. Quite the opposite -- they have to

            • Dark matter is more than a "cop out". If dark matter only explained one thing, it might be a cop-out, but it simultaneously explains observations in cosmology, observations of galactic rotation curves, and large-scale structure formation -- all independent phenomena. This is a nontrivial accomplishment.

              It is a non-trivial accomplishment, but a math problem has been solved, not a physics problem. The numbers line up, but we have a big missing hole which we can't detect.

              It is also not true that no partic

          • Hear, hear.

            I've been quite surprised at the influx of "odd" observations over the past few years; I certainly wasn't expecting local pancake structures.

            You raise a pretty good point, though, on the structure of disks, large and small, in the first place.

            Plasma physicists jump up and down that the in-vogue theories treat large-scale magnetic fields and currents as non-existent, as though charge must cancel out on the large scale, therefore it has no effect. Sometimes, they make a good point - some of t

    • Re:A Quick Question (Score:3, Insightful)

      by khayman80 ( 824400 )
      First of all, the galaxy is believed to have condensed from a much larger cloud of primordial hydrogen and helium (it's theorized that supermassive black holes played a large role in this process). Because the proto-galaxy condensed from something MUCH larger, its moment of inertia reduced dramatically (rather like an ice-skater drawing her arms in to spin faster). This caused the angular rotation of the galaxy to increase around whatever axis the angular momentum pointed originally (which I would imagine

  • So... (Score:5, Funny)

    by unsinged int ( 561600 ) on Saturday April 09, 2005 @12:29PM (#12187572)
    when's the galaxy due to flip over?
  • I wonder if this has anything to do with the conjectured cosmic griddle, which heats the primordial galactic batter and makes it te golden hue of our stars and sun?
  • It was my understanding that HOW it got to be that shape was never a mystery. The real mystery was who in the hell was holding that huge spatula, and where did they get it in the first place?
  • An elven dwarf galaxy? Now that's just perposterous!

  • Had to be done (Score:3, Funny)

    by taylortbb ( 759869 ) <taylor@byrnes.gmail@com> on Saturday April 09, 2005 @12:56PM (#12187712) Homepage
    Yes, but is it perpendicular?

    (ducks)
  • Theorists believed that the eleven dwarf galaxy companions should have a diffuse, spherical arrangement

    Sounds like someone's been watching the Lord of the Rings box set a wee bit much.
  • Hawking: Your theory of a donut shaped universe is intriguing Homer, I may have to steal it.
    Homer: Wow, I can't believe someone I never heard of is hanging out with a guy like me.
  • Mmmmmmmmmm......

    Universalicious
  • Milky way
    Pancakes
    Galaxy

    What next? Black holes look like blackcurrents?
  • I just ended my Friday lecture on the local group of galaxies. They're the best measure of the frequency of galaxies out there in the universe, since many dwarf ellipitcals (very common in the local group) are difficult or impossible to see at greater distances.
  • Anyone else notice that their picture of the Milky Way galaxy has 5 arms? If this is coming from the crack team of scientists, I'm a bit suspicious.
  • Does anyone know which supercomputer they used? I am interested to know because I thought that one that was composed of I don't know how many dual G5s was supposed to be used for astronomy research and the like...
  • The problem here, is that in all likelyhood a galaxy shouldn't be shaped like a pancake, that is unless someone put it together specifically to look that way.

    Argueing there's a logical complex reason why the milky way is a pancake is like arguing there's a complex reason that only 6 cookies remain in the jar, when your mother placed 20 there.

    Try as you might, you're not going to convice your mother that you didn't eat 14 (choak) cookies. The explanation is simple enough, and without solid evidence that s
  • our new yummy buttermilk-flavoured overlords!

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