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WIMPs over MACHOS?

  1. Nov 15, 2015 #1
    I have been thinking about this quite often, and I know that usually WIMPs are taken more seriously than MACHOs, and I know it is because MACHOS don't exist in such huge amounts, but why are they considered better candidates for Dark Matter?
     
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  3. Nov 15, 2015 #2

    Chalnoth

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    The evidence of dark matter is seen clearly in the CMB, which was emitted before any compact objects could have formed.
     
  4. Nov 15, 2015 #3
    Aha, I had been wondering about this quite a while, why have MACHOs been discounted as a DM candidate by most people working on it.
    The idea that DM could be explained by there being a large amount of small material objects which simply are not visible to us because they are too small and dark always did seem like a simplest explanation to me.
    Is the evidence of DM existing in the CMB data a hard certainty, or is it the 'strongly likely' category?
     
  5. Nov 15, 2015 #4

    Chronos

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    There are certain asumptions used that could affect our interpretations regarding dark matter. For example, it is assumed radiation density in the early universe was fixed. If you relax that assumption other interpretations are possible. See http://background.uchicago.edu/~whu/intermediate/driving2.html for discussion. There was a time it was speculated primordial black holes could account for dark matter, but, after extensive study and analysis of the permissible mass range for PBH's has nearly exhausted any possibility of them as a dark matter candidate.
     
  6. Nov 16, 2015 #5

    Jorrie

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  7. Nov 16, 2015 #6

    phyzguy

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    Also, Big Bang Nucleosynthesis very tightly constrains the baryon content of the universe, and the required baryon content is quite consistent with what is derived from the CMB. So the dark matter can not be made of ordinary atoms. This pretty much eliminates MACHOS as a possibility.
     
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