Last modified: December 2018

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

recombination

Context: models

Synopsis

Optically-thin recombination continuum model.

Syntax

recombination

Description

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


Example

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

Create a component of the recombination model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.refer    frozen         5000  1.17549e-38  3.40282e+38  angstroms
   mdl.ampl     thawed            1  1.17549e-38  3.40282e+38  angstroms
   mdl.temperature thawed         3000  1.17549e-38  3.40282e+38     Kelvin
   mdl.fwhm     thawed          100  1.17549e-38  3.40282e+38       km/s

ATTRIBUTES

The attributes for this object are:

refer

The reference point, in Angstroms.

ampl

The amplitude of the emission; it is defined at the reference point but its numerical value there also depends on the temperature.

temperature

The temperature in Kelvin.

fwhm

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

Notes

The functional form of the model for points is:

f(x) = ampl * (refer / x)^2 *
       exp(-1.440E8 * (1 / x - 1 / refer) / temperature)

       if x < refer

     = ampl * exp(-0.5 * (x - refer)^2 / g(fwhm, refer)^2)

       otherwise

g(fwhm, refer) = refer * fwhm / (2.354820044 * c)

where c is the speed of light in km/s. For integrated data sets the low-edge of the grid is used.


Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.