Synopsis
The XSPEC vwdem model: plasma emission, multi-temperature with power-law distribution of emission measure.
Syntax
xsvwdem The xsvwdem model is an additive model component.
Description
The model is described at [1] .
Example
>>> create_model_component("xsvwdem", "mdl")
>>> print(mdl)Create a component of the xsvwdem model and display its default parameters. The output is:
mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.Tmax thawed 1 0.01 20 keV mdl.beta thawed 0.1 0.01 1 mdl.inv_slope thawed 0.25 -1 10 mdl.nH frozen 1 1e-06 1e+20 cm^-3 mdl.He frozen 1 0 10 mdl.C frozen 1 0 10 mdl.N frozen 1 0 10 mdl.O frozen 1 0 10 mdl.Ne frozen 1 0 10 mdl.Na frozen 1 0 10 mdl.Mg frozen 1 0 10 mdl.Al frozen 1 0 10 mdl.Si frozen 1 0 10 mdl.S frozen 1 0 10 mdl.Ar frozen 1 0 10 mdl.Ca frozen 1 0 10 mdl.Fe frozen 1 0 10 mdl.Ni frozen 1 0 10 mdl.Redshift frozen 0 -0.999 10 mdl.switch frozen 2 0 3 mdl.norm thawed 1 0 1e+24
ATTRIBUTES
The attributes for this object are:
| Attribute | Definition |
|---|---|
| Tmax | The maximum temperature for power-law emission measure distribution. |
| beta | The ratio of minimum to maxmum temperature. |
| inv_slope | The inverse of the slope (labelled p in the XSPEC documentation). |
| nH | Fixed at 1 for most applications. |
| He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni | The abundance of the element in solar units. |
| Redshift | The redshift of the plasma. |
| switch | If 0, the mekal code is run to evaluate the model; if 1 then interpolation of the mekal data is used; if 2 then interpolation of APEC data is used; if 3 then SPEX data (only usable with XSPEC 12.14.0 or later). See [1] for more details. This parameter can not be thawed. |
| norm | The normalization of the model: see [1] for an explanation of the units. |
References
- [1] https://heasarc.gsfc.nasa.gov/xanadu/xspec/manual/XSmodelWdem.html
Changes in CIAO
Changed in CIAO 4.17
The maximum value of the switch parameter is now 3.
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.