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Next: vvoigt, zvvoigt: Voigt line Up: Additive Model Components Previous: vlorentz, zvlorentz: lorentz line   Contents


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:

$\displaystyle 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

The line is calculated out to fifty times the maximum of sigma and gamma. Note also that the normalization is defined as the integral over energies greater than zero since negative energies are unphysical.

next up previous contents
Next: vvoigt, zvvoigt: Voigt line Up: Additive Model Components Previous: vlorentz, zvlorentz: lorentz line   Contents