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Amount of dark matter present random or does it correlate w/ cluster characteristics

  1. Aug 25, 2012 #1
    Has dark matter been observed to exist in quantities that correlate with the apparent observed mass or overal volume of gallexy/ star clusters? I'm wondering if dark matter is distributed in relative even amounts based on given characteristics or if it is thought to be random/unknown.
     
    Last edited: Aug 25, 2012
  2. jcsd
  3. Aug 25, 2012 #2

    Drakkith

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    Staff: Mentor

    Re: Amount of dark matter present random or does it correlate w/ cluster characterist

    We cannot observe dark matter directly, only indirectly. The observations of "missing mass" and other oddities is exactly what we use to determine where dark matter is and what it is doing. We have no idea how to measure quantities of it other than the mass of it in a volume of space.

    Edit: Hmm, I'm not sure that answers your question. I believe the distribution is relatively even if we look at very large volumes of space, such as mega-parsec distances, but on the local scale it is very different. Much of the dark matter in the milky way is believed to be in a spherical "halo" around the outskirts of the galaxy.
     
  4. Aug 25, 2012 #3

    Bobbywhy

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    Gold Member

    Re: Amount of dark matter present random or does it correlate w/ cluster characterist

    Rorkster2, You may find information about your question, supplied by marcus on 20 August here in this fourm:

    Astrophysical and cosmological probes of dark matter
    Matts Roos
    17 Aug 2012
    http://arxiv.org/abs/1208.3662v1

    Cheers,
    Bobbywhy
     
  5. Aug 26, 2012 #4

    Chalnoth

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    Re: Amount of dark matter present random or does it correlate w/ cluster characterist

    The ratio of normal matter to dark matter varies quite dramatically from galaxy to galaxy. Smaller galaxies tend to have a much greater relative abundance of dark matter than larger galaxies, in large part because when smaller galaxies form, their gravitational potential wells aren't strong enough to hold in the material from the violent formation of the first stars. So most of the normal matter gets blown away, leaving just a little bit of behind, while the dark matter remains unaffected.
     
    Last edited: Aug 26, 2012
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