xsbvtapec

Context: models

Synopsis

The XSPEC bvtapec model: velocity broadened APEC emission spectrum with separate continuum and line temperatures.

Syntax

xsbvtapec

The xsbvtapec model is an additive model component.

Description

The model is described at [1] . The set_xsxset and get_xsxset functions are used to set and query the XSPEC XSET parameters, in particular the keywords "APECROOT" and "APEC_TRACE_ABUND".

Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.kT       thawed          6.5       0.0808       68.447        keV
   mdl.kTi      thawed          6.5       0.0808       68.447        keV
   mdl.He       frozen            1            0         1000           
   mdl.C        frozen            1            0         1000           
   mdl.N        frozen            1            0         1000           
   mdl.O        frozen            1            0         1000           
   mdl.Ne       frozen            1            0         1000           
   mdl.Mg       frozen            1            0         1000           
   mdl.Al       frozen            1            0         1000           
   mdl.Si       frozen            1            0         1000           
   mdl.S        frozen            1            0         1000           
   mdl.Ar       frozen            1            0         1000           
   mdl.Ca       frozen            1            0         1000           
   mdl.Fe       frozen            1            0         1000           
   mdl.Ni       frozen            1            0         1000           
   mdl.Redshift frozen            0       -0.999           10           
   mdl.Velocity frozen            0            0        10000       km/s
   mdl.norm     thawed            1            0        1e+24

ATTRIBUTES

The attributes for this object are:

Attribute	Definition
kT	Continuum temperature, in keV.
kTi	Line temperature, in keV.
He, C, N, O, Ne, Mg, Al, Si, S, Ar, Ca, Fe, Ni	The abundance of the element in solar units. The trace element abundances are determined by the APEC_TRACE_ABUND xset keyword (the default is 1.0).
Redshift	The redshift of the plasma.
Velocity	The gaussian sigma of the velocity broadening, in km/s.
norm	The normalization of the model: see [1] for an explanation of the units.

References

[1] https://heasarc.gsfc.nasa.gov/xanadu/xspec/manual/XSmodelBtapec.html

Changes in CIAO

Changed in CIAO 4.17

The Redshift and Velocity parameters are now frozen by default to match XSPEC.

Changed in CIAO 4.16

The maximum for the Velocity parameter has been changed from 10^6 to 10^4 km/s.

XSPEC version

CIAO 4.17 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.