darkhistory.physics.coll_exc_xsec¶
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darkhistory.physics.
coll_exc_xsec
(eng, species=None)¶ e-e collisional excitation cross section in cm2.
See 0906.1197.
Parameters: - eng : float or ndarray
Abscissa of kinetic energies.
- species : {‘HI’, ‘HeI’, ‘HeII’}
Species of interest.
Returns: - float or ndarray
e-e collisional excitation cross section.