darkhistory.physics.beta_ion¶
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darkhistory.physics.
beta_ion
(T_rad, species)¶ Case-B photoionization coefficient.
Parameters: - T_rad : float
The radiation temperature.
- species : {‘HI’, ‘HeI_21s’, ‘HeI_23s’}
The relevant species.
Returns: - float
Case-B photoionization coefficient in s-1.
Notes
For HeI, returns beta with respect to the 2s state, in agreement with convention in RECFAST.