Last modified: December 2023

AHELP for CIAO 4.16 Sherpa


Context: models


The XSPEC kerrdisk model: accretion disk line emission with BH spin as free parameter.



The xskerrdisk model is an additive model component.


The model is described at [1] .

Deprecated in Sherpa 4.10.0

The r_brg , rinms , and routms parameters have been renamed to r_br_g , rin_ms , and rout_ms respectively to match the XSPEC definition. The names r_brg , rinms , and routms can still be used to access the parameters, but they will be removed in a future release.


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

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

   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.lineE    frozen          6.4          0.1          100        keV
   mdl.Index1   frozen            3          -10           10           
   mdl.Index2   frozen            3          -10           10           
   mdl.r_br_g   frozen            6            1          400           
   mdl.a        thawed        0.998         0.01        0.998           
   mdl.Incl     frozen           30            0           90        deg
   mdl.Rin_ms   frozen            1            1          400           
   mdl.Rout_ms  frozen          400            1          400           
   mdl.z        frozen            0            0           10           
   mdl.norm     thawed            1            0        1e+24           


The attributes for this object are:

Attribute Definition
lineE The rest-frame line energy, in keV.
Index1 The emissivity index for the inner disk.
Index2 The emissivity index for the outer disk.
r_br_g The break radius separating the inner and outer portions of the disk, in gravitational radii.
a The dimensionless black hole spin.
Incl The disk inclination angle, in degrees. A face-on disk has Incl=0.
Rin_ms The inner radius of the disk, in units of the radius of marginal stability.
Rout_ms The outer radius of the disk, in units of the radius of marginal stability.
z The redshift of the source.
norm The flux in the line, in units of photon/cm^2/s.


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