darkhistory.physics.peebles_C

darkhistory.physics.peebles_C(xHII, rs, fudge=1.125, gauss_fudge=True)

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.

fudge : float

RECFAST fudge factor.

gauss_fudge : bool

Flag for RECFAST gaussian correction.

Returns:

float

The Peebles C factor.

Notes

See https://www.astro.ubc.ca/people/scott/recfast.for for definition of the Recfast Gaussian fudge factors we use.