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Space Science

Simulations Predict Where We Can Find Dark Matter 61

p1234 writes with this excerpt from the Max Planck Institute for Astrophysics: "Simulations by the Virgo team show how the Milky Way's halo grew through a series of violent collisions and mergers from millions of much smaller clumps that emerged from the Big Bang. ... If Fermi does detect the predicted emission from the Milky Way's smooth inner halo, then it may, if we are lucky, also see gamma-rays from small (and otherwise invisible) clumps of dark matter which happen to lie particularly close to the Sun. ... The largest simulation took 3.5 million processor hours to complete. Volker Springel was responsible for shepherding the calculation through the machine and said: 'At times I thought it would never finish.' Max Planck Director, Professor Simon White, remarked that 'These calculations finally allow us to see what the dark matter distribution should look like near the Sun where we might stand a chance of detecting it.'" We discussed a related simulation a few months ago.
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Simulations Predict Where We Can Find Dark Matter

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  • Obvious (Score:2, Funny)

    by Anonymous Coward
    I can't believe no one has tried looking for dark matter directly next to the Sun. That should light it up!
  • by Anonymous Coward

    Instead of a gamma-ray glow map as seen from the Sun, I'd like to see 3d renderings of a whole galaxy where they artificially color dark matter to show where it is.

    • by vrmlguy ( 120854 )

      Instead of a gamma-ray glow map as seen from the Sun, I'd like to see 3d renderings of a whole galaxy where they artificially color dark matter to show where it is.

      I believe that was the first picture []. Of course it was 2-D in the article, but it had to have been based off of a 3-D model. Maybe the researchers could create a Quicktime VR movie that we could spin.

  • Hmmm (Score:3, Interesting)

    by AlphaLop ( 930759 ) on Saturday November 08, 2008 @04:17AM (#25686099)
    Sounds like with that many computer hours needed they should set up something similar to Seti@home
    • Re:Hmmm (Score:4, Informative)

      by Anonymous Coward on Saturday November 08, 2008 @10:12AM (#25687179)

      Sounds like with that many computer hours needed they should set up something similar to Seti@home

      N-body simulations require a high degree of communications between processing nodes, something "@home" systems don't provide.

  • that sounds a pretty useless measurement

    my mid range processor does about 0.5GFLOPS, which means those available on the market probably range from about 0.1-2GFLOPS give or take, and then theres graphics processors, which are capable of TFLOPS these days, so there could be a factor of about 10^4 in the number of FLOP's done, i know that astrophysics often has order of magnitude calculations, but that's just a bit useless
    • Processor hours are the right unit if you're trying to allocate usage of a large computer; in particular, they're the units in which compute power on large national clusters is requested in grants.

      The calculation in this article was done at the LRZ in Munich, which consists of nineteen 512-core 1.6GHz Itanium systems; 3.5 million processor hours corresponds to using nine of those nineteen systems for a month.

  • I find (Score:4, Funny)

    by Konster ( 252488 ) on Saturday November 08, 2008 @06:05AM (#25686373)

    I find plenty of dark matter when I turn out all the lights prior to going to bed for the evening.

    Specifically, I find plenty of dark matter with my toes, which doesn't result in a shout of discovery like, "Eureka!" but ,"*$&#@!"

  • by K. S. Kyosuke ( 729550 ) on Saturday November 08, 2008 @07:06AM (#25686561)

    LAUNCELOT: Look, my liege!

    ARTHUR: Camelot!

    GALAHAD: Camelot!

    LAUNCELOT: Camelot!

    PATSY: It's only a model.

    ARTHUR: Shhh!

  • ... also knows where it can find dark matter. And it doesn't need teraflops to do so !

  • by vrmlguy ( 120854 ) <> on Saturday November 08, 2008 @11:27AM (#25687551) Homepage Journal

    Due to the proximity to the Sun, the Galactic centre is the brightest and most extended source. This makes it easier to detect than any of the small dark matter subclumps that are distributed over the sky. If one of them should also be detected, it may be devoid of any stars.

    I'm interested in that last sentence. Does the gamma radiation push away hydrogen and dust, preventing the formation of stars, or does dark matter exhibit a repulsive gravitational force, clearing a region of space around it? Without referring to Wikipedia, the latter seems unlikely, but the former seems like something we should worry about. How much gamma radiation are we talking about? Should we worry about one of these clumps drifting near the solar system and sterilizing everything? (And if so, how much of an effect would these clumps have on the Drake equation?)

    • Re: (Score:3, Informative)

      by ceoyoyo ( 59147 )

      I got the impression what they meant was that instead of looking at the core of a galaxy (where the dark matter is most concentrated but there are also guaranteed to be lots of stars) you stand a better chance of detecting it if you look out a little further where there are still some decent clumps but there are many fewer stars. If you get really lucky you might even find a clump that has very few stars in it.

    • Re: (Score:3, Informative)

      Don't read too much into that sentence. They're just saying that if they found a clump without stars inside it, then one can immediately rule out a star-based source of gamma radiation.

      If they don't rule that out, then it will be hard to argue that the gamma rays are from dark matter, and not some other more mundane source.

    • That statement is not what most astrophysicists would say. The Galactic center contains so many "normal" astrophysical sources that it is more likely to to detect dark matter in the halo or in dwarf galaxies.
  • I wonder how many days 3.5 million processor hours actually is. I run SETI@home still, I wonder if that's comparable.

The best defense against logic is ignorance.