Last modified: December 2023

AHELP for CIAO 4.16 Sherpa


Context: models


The XSPEC optxagn model: Colour temperature corrected disc and energetically coupled Comptonisation model for AGN.



The xsoptxagn model is an additive model component.


The model is described at [1] .

Deprecated in Sherpa 4.10.0

The loglledd parameter has been renamed logloledd to match the XSPEC definition. The name loglledd can still be used to access the parameter, but this name will be removed in a future release.


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

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

   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.mass     frozen        1e+07            1        1e+09      solar
   mdl.dist     frozen          100         0.01        1e+09        Mpc
   mdl.logLoLEdd thawed           -1          -10            2           
   mdl.astar    frozen            0            0        0.998           
   mdl.rcor     thawed           10            1          100         rg
   mdl.logrout  frozen            5            3            7           
   mdl.kT_e     thawed          0.2         0.01           10        keV
   mdl.tau      thawed           10          0.1          100           
   mdl.Gamma    thawed          2.1          0.5           10           
   mdl.fpl      thawed       0.0001            0          0.1           
   mdl.fcol     frozen          2.4            1            5           
   mdl.tscat    frozen       100000        10000       100000           
   mdl.Redshift frozen            0            0           10           
   mdl.norm     thawed            1            0        1e+24           


The attributes for this object are:

Attribute Definition
mass The black hole mass in solar masses.
dist The comoving (proper) distance in Mpc.
logLoLEdd The Eddington ratio.
astar The dimensionless black hole spin.
rcor The coronal radius in Rg=GM/c^2. See [1] for more details.
logrout The log of the outer radius of the disk in units of Rg. See [1] for more details.
kT_e The electron temperature for the soft Comptonisation component (soft excess), in keV.
tau The optical depth of the soft Comptonisation component. If this parameter is negative then only the soft Compton component is used.
Gamma The spectral index of the hard Comptonisation component ('power law') which has temperature fixed to 100 keV.
fpl The fraction of the power below rcor which is emitted in the hard comptonisation component. If this parameter is negative then only the hard Compton component is used.
fcol The colour temperature correction to apply to the disc blackbody emission for radii below rcor with effective temperature > tscat.
tscat The effective temperature limit, in K, used in the colour temperature correction.
Redshift The redshift.
norm The normalization of the model. It must be frozen.


XSPEC version

CIAO 4.16 comes with support for version 12.13.1e of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;


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

See Also