Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/emissionlorentz.html
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AHELP for CIAO 4.11 Sherpa v1

emissionlorentz

Context: models

Synopsis

Lorentz function for modeling emission.

Syntax

emissionlorentz

Description

It is for use when the independent axis is in Angstroms.


Example

>>> create_model_component("emissionlorentz", "mdl")
>>> print(mdl)

Create a component of the emissionlorentz 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.flux     thawed            1 -3.40282e+38  3.40282e+38           
   mdl.kurt     frozen            2 -3.40282e+38  3.40282e+38           

ATTRIBUTES

The attributes for this object are:

fwhm

The full-width half-maximum of the model in km/s.

pos

The center of the lorentzian, in Angstroms.

flux

The normalisation of the lorentzian.

kurt

The kurtosis of the lorentzian.

Notes

The functional form of the model for points is:

f(x) = flux * 2 * pi * s / l(x)

l(x) = abs(x - pos)^kurt + (0.5 * s)^2

s = pos * fwhm / c

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.

See Also

models
absorptionlorentz, emissiongaussian, emissionvoigt