voigt, zvoigt: Voigt line profile

A Voigt line profile. The Voigt profile is the convolution of a Gaussian and a Lorentzian. It can be written as:

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

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 in keV
par3	$\gamma$, lorentzian FWHM line width in keV
Norm	$K$, total photons/cm$^{-2}$/s in the line

For zvoigt the parameters are:

par1	$E_l$, line energy in keV
par2	$\sigma$, gaussian line width in keV
par3	$\gamma$, lorentzian FWHM line width in keV
par4	$z$, redshift
Norm	$K$, total photons/cm$^{-2}$/s in the line

Both the gaussian and lorentzian lines are truncated at the point that the integrated flux under the line is within a critical value of the total flux. This critical value can be changed using xset LINECRITLEVEL. The default critical value is $1.0\times10^{-6}$. Note also that the normalization is defined as the integral over energies greater than zero since negative energies are unphysical.

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Last modified: Wednesday, 12-Mar-2025 17:05:25 EDT