Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/xsgrad.html
AHELP for CIAO 4.11 Sherpa v1

xsgrad

Context: models

Synopsis

The XSPEC grad model: accretion disk, Schwarzschild black hole.

Syntax

xsgrad

The xsgrad model is an additive model component.

Description

The model is described at [1] .

Deprecated in Sherpa 4.10.0

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


Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.D        frozen           10            0        10000        kpc
   mdl.i        frozen            0            0           90        deg
   mdl.Mass     thawed            1            0          100      solar
   mdl.Mdot     thawed            1            0          100       1e18
   mdl.TclovTef frozen          1.7            1           10           
   mdl.refflag  frozen            1           -1            1           
   mdl.norm     thawed            1            0        1e+24           

ATTRIBUTES

The attributes for this object are:

D

The distance to the source in kpc.

i

The disk inclination angle, in degrees. A face-on disk has i=0.

Mass

The mass of the central object, in solar masses.

Mdot

The mass accretion rate in units of 10^18 g/s.

TclovTef

The spectral hardening factor, Tcol/Teff. See [1] for more details.

refflag

A flag to control the relativistic effects: if positive then a relativistic calculation is used; if zero or negative then a Newtonian calculation is used. See [1] for more details. This parameter can not be thawed.

norm

The normalization of the model. It should be fixed to 1.

References

XSPEC version

CIAO 4.11 comes with support for version 12.10.0e of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;
print(xspec.get_xsversion())'
12.10.0e

Bugs

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