Last modified: December 2021

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/xsvvwdem.html
AHELP for CIAO 4.14 Sherpa

xsvvwdem

Context: models

Synopsis

The XSPEC vvwdem model: plasma emission, multi-temperature with power-law distribution of emission measure.

Syntax

xsvvwdem

The xsvvwdem model is an additive model component.

Description

The model is described at [1] .


Example

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

Create a component of the xsvvwdem 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.H        frozen            1            0         1000           
   mdl.He       frozen            1            0         1000           
   mdl.Li       frozen            1            0         1000           
   mdl.Be       frozen            1            0         1000           
   mdl.B        frozen            1            0         1000           
   mdl.C        frozen            1            0         1000           
   mdl.N        frozen            1            0         1000           
   mdl.O        frozen            1            0         1000           
   mdl.F        frozen            1            0         1000           
   mdl.Ne       frozen            1            0         1000           
   mdl.Na       frozen            1            0         1000           
   mdl.Mg       frozen            1            0         1000           
   mdl.Al       frozen            1            0         1000           
   mdl.Si       frozen            1            0         1000           
   mdl.P        frozen            1            0         1000           
   mdl.S        frozen            1            0         1000           
   mdl.Cl       frozen            1            0         1000           
   mdl.Ar       frozen            1            0         1000           
   mdl.K        frozen            1            0         1000           
   mdl.Ca       frozen            1            0         1000           
   mdl.Sc       frozen            1            0         1000           
   mdl.Ti       frozen            1            0         1000           
   mdl.V        frozen            1            0         1000           
   mdl.Cr       frozen            1            0         1000           
   mdl.Mn       frozen            1            0         1000           
   mdl.Fe       frozen            1            0         1000           
   mdl.Co       frozen            1            0         1000           
   mdl.Ni       frozen            1            0         1000           
   mdl.Cu       frozen            1            0         1000           
   mdl.Zn       frozen            1            0         1000           
   mdl.Redshift frozen            0       -0.999           10           
   mdl.switch   frozen            2 -3.40282e+38  3.40282e+38           
   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.
H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn The abundance of the element in solar units.
Redshift The redshift of the plasma.
switch What model to use: 0 calculates with MEKAL, 1 interpolates with MEKAL, and 2 interpoates with APEC.
norm The normalization of the model: see [1] for an explanation of the units.

References

Changes in CIAO

New in CIAO 4.14

The xsvvwdem model (added in XSPEC 12.12.0) is new in CIAO 4.14.

XSPEC version

CIAO 4.14 comes with support for version 12.12.0 of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;
print(xspec.get_xsversion())'
12.12.0

Bugs

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

See Also

models
xsvwdem