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| Decoupling of Neutrinos and the |
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| Neutrino
Barrier |
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| • | Now we can
write the energy density |
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| and solve for
temperature: |
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| • | Note then that
timescales for expansion |
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| and decoupling
are the same for T = 12 |
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| billion K at t
= 0.7 sec (kT = 1 MeV). This |
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| is the
neutrino barrier, the limit of any |
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| possible
neutrino astronomy. Note also |
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| these depend
only on fundamental #s. |
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