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voigtabs, zvoigtabs: voigt absorption line

A voigt absorption line as a multiplicative model. The zvoigtabs variant includes redshift as a parameter.

$\displaystyle M(E) = exp(-d*v(E)) $

where $v(E)$ is the voigt line shape:

$\displaystyle v(E) = Re[w(z)] / (\sigma\sqrt{(2\pi)}) $

where $w(z) = exp(-z^2) erfc(-iz)$ is the Faddeeva function, and $z = (E-E_l + i\gamma/2)/(\sqrt{2}\sigma)$

The parameters are:

par1 $E_l$, line energy in keV.
par2 $\sigma$, gaussian line width (sigma) in keV.
par3 $\gamma$, lorentz line width (FWHM) in keV.
par4 $d$, line depth in keV.

For zvoigtabs the parameters are:

par1 $E_l$, line energy in keV.
par2 $\sigma$, gaussian line width (sigma) in keV.
par3 $\gamma$, lorentz line width (FWHM) in keV.
par4 $d$, line depth in keV.
par5 $z$, redshift

See also the voigt model.