Last modified: December 2025

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

xskyconv

Context: models

Synopsis

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

Syntax

xskyconv

The xskyconv model is a convolution model component.

Description

The model is described at [1] .


Example

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

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

mdl
   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
   mdl.ms       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           

ATTRIBUTES

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.

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.