darkhistory.physics.C_He

darkhistory.physics.C_He(xHII, xHeII, rs, species)

Helium C coefficients.

These coefficients play a similar role to the Peebles C factor.

Parameters:

xHIIfloat

The HI ionization fraction nHII/nH.

xHeIIfloat

The HeI ionization fraction nHeII/nH.

rsfloat

The redshift in 1+z.

species{‘singlet’, ‘triplet’}

The relevant helium C coefficient to return.

Returns:

float

The C coefficient.