    The XSPEC vgnei model: collisional plasma, non-equilibrium, temperature evolution.

xsvgnei
The xsvgnei model is an additive model component.

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 keyword "NEIVERS".

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

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

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

mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.kT thawed 1 0.0808 79.9 keV mdl.H frozen 1 0 1 mdl.He frozen 1 0 10000 mdl.C frozen 1 0 10000 mdl.N frozen 1 0 10000 mdl.O frozen 1 0 10000 mdl.Ne frozen 1 0 10000 mdl.Mg frozen 1 0 10000 mdl.Si frozen 1 0 10000 mdl.S frozen 1 0 10000 mdl.Ar frozen 1 0 10000 mdl.Ca frozen 1 0 10000 mdl.Fe frozen 1 0 10000 mdl.Ni frozen 1 0 10000 mdl.Tau thawed 1e+11 1e+08 5e+13 s/cm^3 mdl.meankT thawed 1 0.0808 79.9 keV mdl.redshift frozen 0 -0.999 10 mdl.norm thawed 1 0 1e+24

ATTRIBUTES

The attributes for this object are:

Attribute
Definition
kT
The temperature of the plasma, in keV.
H
The H abundance: it should be set to 0 to switch on and 1 to switch off the free-free continuum.
He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni
The abundance of the element, with respect to Solar.
Tau
The ionization timescale in units of s/cm^3.
meankT
The ionization timescale averaged plasma temperature in keV.
redshift
The redshift of the plasma.
norm
The normalization of the model: see [1] for an explanation of the units.

References

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

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; print(xspec.get_xsversion())'12.13.1e

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

December 2023