Last modified: December 2025

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

xsplcabs

Context: models

Synopsis

The XSPEC plcabs model: powerlaw observed through dense, cold matter.

Syntax

xsplcabs

The xsplcabs model is an additive model component.

Description

The model is described at [1] .


Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.nH       thawed            1            0        1e+06 10^22 atoms / cm^2
   mdl.nmax     frozen            1 -3.40282e+38  3.40282e+38           
   mdl.FeAbun   frozen            1            0           10           
   mdl.FeKedge  frozen         7.11            7           10        KeV
   mdl.PhoIndex thawed            2           -3           10           
   mdl.HighECut frozen           95         0.01          200        keV
   mdl.foldE    frozen          100            1        1e+06           
   mdl.acrit    frozen            1            0            1           
   mdl.FAST     frozen            0 -3.40282e+38  3.40282e+38           
   mdl.Redshift frozen            0       -0.999           10           
   mdl.norm     thawed            1            0        1e+24           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
nH The column density, in units of 10^22 cm^-2.
nmax The maximum number of scatterings. This parameter can not be thawed.
FeAbun The iron abundance.
FeKedge The energy of the Fe K edge, in keV.
PhoIndex The power law photon index.
HighECut The high-energy cut-off threshold energy, in keV.
foldE The high-energy cut-off e-folding energy, in keV.
acrit The critical albedo for switching to elastic scattering. See [1] for more details.
FAST If set to a value above 1, use a mean energy shift instead of integration. This parameter can not be thawed.
redshift The redshift of the source.
norm The normalization of the model.

References

[1]

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.