xsbvcheb6

Context: models

Synopsis

The XSPEC bvcheb6 model: differential emission measure using 6-order Chebyshev polynomial.

Syntax

xsbvcheb6

The xsbvcheb6 model is an additive model component.

Description

The model is described at [1] .

Example

>>> create_model_component("xsbvcheb6", "mdl")
>>> print(mdl)

Create a component of the xsbvcheb6 model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.CPcoef1  thawed            1           -1            1           
   mdl.CPcoef2  thawed          0.5           -1            1           
   mdl.CPcoef3  thawed          0.5           -1            1           
   mdl.CPcoef4  thawed          0.5           -1            1           
   mdl.CPcoef5  thawed          0.5           -1            1           
   mdl.CPcoef6  thawed          0.5           -1            1           
   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.Velocity frozen            0            0        10000       km/s
   mdl.switch   frozen            2            0            3           
   mdl.norm     thawed            1            0        1e+24

ATTRIBUTES

The attributes for this object are:

Attribute	Definition
CPcoef1, CPcoef2, CPcoef3, CPcoef4, CPcoef5, CPcoef6	Chebyshev polynomial coefficients.
nH	H density, in cm^-3.
He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni	The abundance relative to Solar.
Redshift	The redshift of the plasma.
Velocity	The gaussian sigma for the velocity broadening (in km/s) which is only used when switch > 1.
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. See [1] for more details. This parameter can not be thawed.
norm	The normalization of the model.

References

[1] https://heasarc.gsfc.nasa.gov/xanadu/xspec/manual/XSmodelCheb6.html

Changes in CIAO

Added in CIAO 4.17

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.