darkhistory.physics.peebles_C¶
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darkhistory.physics.
peebles_C
(xHII, rs)¶ Hydrogen Peebles C coefficient.
This is the ratio of the total rate for transitions from n = 2 to the ground state to the total rate of all transitions, including ionization.
Parameters: - xHII : float
The ionization fraction nHII/nH.
- rs : float
The redshift in 1+z.
Returns: - float
The Peebles C factor.