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Dark Matter Mapped in a Supercluster of Galaxies

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  • jefftibb
    Breaking News from SPACE.COM When astronomers observe other galaxies and the universe as a whole, they see effects of gravity that cannot be explained by the
    Message 1 of 1 , Apr 11, 2002
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      Breaking News from SPACE.COM

      When astronomers observe other galaxies and the universe as a whole,
      they see effects of gravity that cannot be explained by the stars,
      gas, dust and other matter they find. Something else must be there.

      That something else is called dark matter. No one has ever seen it,
      and nobody knows exactly what it is. But researchers are beginning to
      map the mysterious stuff, which is thought to make up roughly 80
      percent of all the matter in the universe.

      Along the way, studies have indicated that dark matter clumps
      together and may act as the seeds for galaxy formation. Dark matter
      also seems to hold clusters of galaxies together, which in turn are
      bonded into superclusters.

      Today at the UK National Astronomy Meeting, Andrew Taylor of the
      Royal Observatory in Edinburgh will present what he says is the most
      accurate map ever made of the dark matter in a galactic supercluster.

      Taylor and colleagues used a trick of the cosmos called gravitational
      lensing, in which light from a distant galaxy is bent by the
      gravitational field of matter in front of it. The lensing allowed
      them to probe the Abell 901 and 902 supercluster, one of the largest
      structures in the Universe.

      The enormous gathering of galaxies, some 10 million light years
      across, actually contains a group of galaxy clusters known as Abell
      901a, 901b and Abell 902.

      From pictures that cover an area of sky the size of the full Moon and
      where 50,000 galaxies reside, the researchers created a map of dark
      matter. It shows that not only do the galaxies lie within larger dark
      matter clumps, but that these clumps are connected by "cosmic
      filaments" -- bridges of dark matter connecting the clusters.

      The existence of these filaments, and a resulting "cosmic web," has
      long been a prediction of dark matter theorists.

      The results were published in the March 20 issue of the Astrophysical
      Journal. More recent work by Taylor is expected to allow cosmologists
      to make fully three-dimensional images of dark matter distribution.


      http://www.space.com/scienceastronomy/astronomy/dark_matter_020410.htm
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