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Key points –
we are pretty darn certain it is
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present in
larger quantities than baryons.
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Can provide
the extra gravity, extra unseen
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perturbation,
to let galaxies grow from the
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small observed
temperature fluctuations.
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Unknown what
it is! Recall our previous class
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discussion
(chapter 2).
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Terminology
in this game describes “hot” and
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“cold” dark
matter, indicating whether or not
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particles are
relativistic when they decouple.
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