Voigt function for modeling absorption (equivalent width).
This model uses an AbsorptionGaussian component to model the core of the profile and an AbsorptionLorentz component to model the wings of the absorption feature. This model is intended to be used to modify another model (e.g. by multiplying the two together). It is for use when the independent axis is in Angstroms.
>>> create_model_component("absorptionvoigt", "mdl") >>> print(mdl)
Create a component of the absorptionvoigt model and display its default parameters. The output is:
mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.center frozen 5000 1.17549e-38 3.40282e+38 angstroms mdl.ew thawed 1 1.17549e-38 3.40282e+38 angstroms mdl.fwhm thawed 100 1.17549e-38 3.40282e+38 km/s mdl.lg thawed 1 1.17549e-38 3.40282e+38
The attributes for this object are:
The center of the profile, in Angstroms.
The equivalent width of the profile. The ewidth parameter of the Gaussian and Lorentz sub-components is set to half this value.
The full-width half-maximum of the model in km/s.
The fwhm parameters of the Gaussian and Lorentz components are set based on the fwhm and lg values: the Gaussian component has its fwhm parameter set equal to fwhm , and the Lorentz component has its fwhm parameter set to lg * fwhm .
The Voigt function is approximated by the sum of a Gaussian and a Lorentzian profile (  ), which works best when the ratio between the FWHM of the Gaussian and Lorentzian sub-components is near unity. The flux value is always kept evenly divided in between each sub-component. The FWHM of each sub-component is related to that of the other sub-component via the lg parameter.
-  Lang, Astrophysical Formulae, 1980, 2nd ed., page 220
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