Last modified: December 2023

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

xstbgrain

Context: models

Synopsis

The XSPEC TBgrain model: ISM grain absorption.

Syntax

xstbgrain

The xstbgrain model is a multiplicative model component.

Description

The model is described at [1] .


Example

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

Create a component of the xstbgrain 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.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           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
nH The equivalent hydrogen column (in units of 10^22 atoms/cm^2).
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.

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, xstbpcf, xstbrel, xstbvarabs, xsztbabs