Last modified: December 2023

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/xstbvarabs.html
AHELP for CIAO 4.16 Sherpa

xstbvarabs

Context: models

Synopsis

The XSPEC TBvarabs model: ISM grain absorption.

Syntax

xstbvarabs

The xstbvarabs model is a multiplicative model component.

Description

The model is described at [1] .


Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.nH       thawed            1            0        1e+06 10^22 atoms / cm^2
   mdl.He       frozen            1            0            1           
   mdl.C        frozen            1            0            1           
   mdl.N        frozen            1            0            1           
   mdl.O        frozen            1            0            1           
   mdl.Ne       frozen            1            0            1           
   mdl.Na       frozen            1            0            1           
   mdl.Mg       frozen            1            0            1           
   mdl.Al       frozen            1            0            1           
   mdl.Si       frozen            1            0            1           
   mdl.S        frozen            1            0            1           
   mdl.Cl       frozen            1            0            1           
   mdl.Ar       frozen            1            0            1           
   mdl.Ca       frozen            1            0            1           
   mdl.Cr       frozen            1            0            1           
   mdl.Fe       frozen            1            0            1           
   mdl.Co       frozen            1            0            1           
   mdl.Ni       frozen            1            0            1           
   mdl.H2       frozen          0.2            0            1           
   mdl.rho      frozen            1            0            5     g/cm^3
   mdl.amin     frozen        0.025            0         0.25        mum
   mdl.amax     frozen         0.25            0            1        mum
   mdl.PL       frozen          3.5            0            5           
   mdl.H_dep    frozen            1            0            1           
   mdl.He_dep   frozen            1            0            1           
   mdl.C_dep    frozen            1            0            1           
   mdl.N_dep    frozen            1            0            1           
   mdl.O_dep    frozen            1            0            1           
   mdl.Ne_dep   frozen            1            0            1           
   mdl.Na_dep   frozen            1            0            1           
   mdl.Mg_dep   frozen            1            0            1           
   mdl.Al_dep   frozen            1            0            1           
   mdl.Si_dep   frozen            1            0            1           
   mdl.S_dep    frozen            1            0            1           
   mdl.Cl_dep   frozen            1            0            1           
   mdl.Ar_dep   frozen            1            0            1           
   mdl.Ca_dep   frozen            1            0            1           
   mdl.Cr_dep   frozen            1            0            1           
   mdl.Fe_dep   frozen            1            0            1           
   mdl.Co_dep   frozen            1            0            1           
   mdl.Ni_dep   frozen            1            0            1           
   mdl.redshift frozen            0       -0.999           10           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
nH The equivalent hydrogen column (in units of 10^22 atoms/cm^2).
He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, Ar, Ca, Cr, Fe, Co, Ni The abundance of the element in solar units.
H2 The equivalent molecular hydrogen column (in units of 10^22 atoms/cm^2).
rho The grain density, in g/cm^3.
amin The minimum grain size, in micro-meters.
amax The maximum grain size, in micro-meters.
PL The power-law index of grain sizes.
H_dep, He_dep, C_dep, N_dep, O_dep, Ne_dep, Na_dep, Mg_dep, Al_dep, Si_dep, S_dep, Cl_dep, Ar_dep, Ca_dep, Cr_dep, Fe_dep, Co_dep, Ni_dep The grain depletion fraction of the element.
redshift The redshift of the absorber.

Notes

The `set_xsabund` function changes the relative abundances of the elements, in particular the "wilm" setting.

References

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

Bugs

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

See Also

models
xstbabs, xstbfeo, xstbgas, xstbgrain, xstbpcf, xstbrel, xsztbabs