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Imaging the distribution of dark matter-anyone want to expand on this?

  1. Dec 14, 2006 #1


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    Dearly Missed

  2. jcsd
  3. Dec 14, 2006 #2


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    Their method sounds good for the SKA - which isn't built yet.
  4. Dec 14, 2006 #3

    Hans de Vries

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    There was an IBM press release on the Square Kilometer Array (SKA) radio
    telescope just last week:


    Regards, Hans
  5. Dec 14, 2006 #4


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    the young researcher who made the map, Stefan Hilbert, is at the Max Planck Instutite for Astrophysics at Garching.
    He was using an idea of how to "see" dark matter which was proposed by Metcalf and White, also at MPI Garching, in this paper:

    A map was produced showing the [dark matter] mass distribution over a patch of sky about one quarter of the area of the Full Moon.

    The method looks for distortions in the background of ancient neutral hydrogen (21 cm) radiation, from before the galaxies coagulated ("curdled"), at a time when the structure of the universe and the distribution of matter were more uniform.
    Different layers of 21 cm radiation going back in time different amounts can be distinguished by their redshift.
    The distortion of each layer is used to reconstruct the distribution of dark matter between us and the source of radiation.

    The map or image of dark matter seems to have been synthesized from many separate observations by radio telescopes of this hydrogen radiation.
    It is in a sense a "mosaic" because he used a computer to combine many different observations into one big image---that is AS IF it had been made by a very large radio telescope (larger than any now available).

    For us in the "Beyond Standard" context, information about dark energy and dark matter is of interest because
    either the standard model of gravity (Gen Rel) has to be modified in how it behaves at long distance---to account for DM and DE effects---
    or the standard matter model has to be supply, or be modified to supply, particles and fields to account for these effects.
    The observed DM and DE effects present one of the main challenges which motivates beyond standard extensions of Gen Rel and QFT.
    Last edited: Dec 14, 2006
  6. Dec 15, 2006 #5
    It seems to be a widely spread misconception that the bending of light provides "direct" evidence of dark matter. An observation of lightbending only indicates that something has to exist which causes the bending (which does not contain so much information :tongue: ). If one then ASSUMES that the lightbending is due to gravitation, one could infer the presence of unseen (dark) matter. Direct evidence of dark matter should be that one can interact with it, study it in particle accelerators, etc.
    Personally, I don't believe in dark matter at all (see http://home.online.no/~avannieu/darkmatter/ ). The desperate and incredable research going on in this field will later be considered as the biggest historical scientific blunder of all times.
    Last edited by a moderator: Apr 22, 2017
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