Last modified: December 2023

AHELP for CIAO 4.16 Sherpa


Context: models


The XSPEC kyconv convolution model: convolution using a relativistic line from axisymmetric accretion disk



The xskyconv model is a convolution model component.


The model is described at [1] .


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

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

   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.a        thawed       0.9982            0            1       GM/c
   mdl.theta_o  thawed           30            0           89        deg
   mdl.rin      frozen            1            1         1000     GM/c^2       frozen            1            0            1           
   mdl.rout     frozen          400            1         1000     GM/c^2
   mdl.alpha    frozen            3          -20           20           
   mdl.beta     frozen            3          -20           20           
   mdl.rb       frozen          400            1         1000     GM/c^2
   mdl.zshift   frozen            0       -0.999           10           
   mdl.limb     frozen            0            0            2           
   mdl.ne_loc   frozen          100            3         5000           
   mdl.normal   frozen            1           -1          100           


The attributes for this object are:

Attribute Definition
a a/M, the black-hole angular momentum in (GM/c).
theta_o The observer inclination in degrees (0 is pole on).
rin The inner radius, in GM/c^2.
ms Flag: 0 means integrate from rin, 1 means integrate the emission from above the marginally-stable orbit only.
rout The outer radius, in GM/c^2.
alpha The accretion disk emissivity scales as r^-alpha for r < rb.
beta The accretion disk emissivity scales as r^-beta for r > rb.
rb The boundary radius between inner and outer emissivity laws, in units of GM/c^2.
zshift The overall Doppler shift.
limb Flag: 0 means isotropic emission, 1 means Laor's limb darkening (1 + 0.26 mu), 2 means Haardt's limb brightening (log(1 + 1 / mu)).
ne_loc The number of grid points in local energy (energy resolution of local flux, the grid is equidistant in logarithmic scale).
normal Flag: 0 means normalize total flux to unity, > 0 means normalize to unity at the energy given by the parameter value, and < 0 means unnormalized.


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


Changes in CIAO

Added in CIAO 4.13

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.