Synopsis
The XSPEC vtapec model: APEC emission spectrum with separate continuum and line temperatures.
Syntax
xsvtapec The xsvtapec 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", "APECTHERMAL", "APECVELOCITY", "APECNOLINES", and "APEC_TRACE_ABUND".
Example
>>> create_model_component("xsvtapec", "mdl")
>>> print(mdl)Create a component of the xsvtapec 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.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. |
| norm | The normalization of the model: see [1] for an explanation of the units. |
References
- [1] https://heasarc.gsfc.nasa.gov/xanadu/xspec/manual/XSmodelTapec.html
Changes in CIAO
Changed in CIAO 4.17
The Redshift parameter is now frozen by default to match XSPEC.
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.