Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/xstbgrain.html
AHELP for CIAO 4.11 Sherpa v1

xstbgrain

Context: models

Synopsis

The XSPEC TBgrain model: ISM grain absorption.

Syntax

xstbgrain

The xstbgrain model is a multiplivative 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       100000 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:

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 4.11 comes with support for version 12.10.0e of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;
print(xspec.get_xsversion())'
12.10.0e

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