Cosmological visibility function (source code)

= Cosmological visibility function
{title2=$g(\eta)$}
{wiki=Recombination_(cosmology)#Visibility_function}

The visibility function
$$
g(\eta)=\partial_\eta e^{-\tau(\eta)}
=\Gamma(\eta)e^{-\tau(\eta)}
$$
is the probability density for the conformal time of a CMB photon's last scattering.