Synopsis
Lorentz function for modeling absorption (equivalent width).
Syntax
absorptionlorentz
Description
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.
Example
>>> create_model_component("absorptionlorentz", "mdl") >>> print(mdl)
Create a component of the absorptionlorentz model and display its default parameters. The output is:
mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.fwhm thawed 100 1.17549e-38 3.40282e+38 km/s mdl.pos frozen 5000 1.17549e-38 3.40282e+38 angstroms mdl.ewidth thawed 1 -3.40282e+38 3.40282e+38
ATTRIBUTES
The attributes for this object are:
Attribute | Definition |
---|---|
fwhm | The full-width half-maximum of the model in km/s. |
pos | The center of the lorentzian, in Angstroms. |
ewidth | The equivalent width of the model, in Angstroms. |
Notes
The functional form of the model for points is:
f(x) = 1 - ewidth * c / (1.571 * fwhm * pos * l(x)) l(x) = 1 + 4 * ((1 / x - 1 / pos) * pos * c / fwhm)^2 c = speed of light in km/s
and for integrated data sets the low-edge of the grid is used.
The speed of light can be found by inspecting the module variable sherpa.astro.optical.c_km .
Bugs
See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.