darkhistory.physics.beta_ion¶
- darkhistory.physics.beta_ion(T_rad, species)¶
Case-B photoionization coefficient.
- Parameters:
- T_radfloat
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.