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The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.


vvoigt, zvvoigt: Voigt line profile with widths in km/s

A Voigt line profile with both $\sigma$ and $\gamma$ in km/s. 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(E_l/c)\sqrt{(2\pi)})
$

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

The parameters are:

par1 $E_l$, line energy in keV
par2 $\sigma$, gaussian line width in km/s
par3 $\gamma$, lorentzian FWHM line width in kms/
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 km/s
par3 $\gamma$, lorentzian FWHM line width in km/s
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.