Last modified: December 2025

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/xsthcomp.html
AHELP for CIAO 4.18 Sherpa

xsthcomp

Context: models

Synopsis

The XSPEC thcomp convolution model: Thermally comptonized continuum.

Syntax

xsthcomp

The xsthcomp model is a convolution model component.

Description

The model is described at [1] .


Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.Gamma_tau thawed          1.7        1.001           10           
   mdl.kT_e     thawed           50          0.5          150        keV
   mdl.cov_frac thawed            1            0            1           
   mdl.z        frozen            0            0            5           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
Gamma_tau The low-energy power-law photon index when positive and the Thomson optical depth (multiplied by -1) when negative.
kT_e The electron temperature (high energy rollover)
cov_frac The scattering fraction (between 0 and 1). If 1 then all of the seed photons will be Comptonized, and if 0 then only the original seed photons will be seen.
z redshift

Notes

Unlike XSPEC, the convolution model is applied directly to the model, or models, rather than using the multiplication symbol.

References

[1]

Changes in CIAO

Added in CIAO 4.13

XSPEC version

CIAO 4.18 comes with support for version 12.14.0k of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;
print(xspec.get_xsversion())'
12.14.0k

Bugs

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

See Also

models
xsnthcomp