    The XSPEC TBrel model: ISM grain absorption.

xstbrel
The xstbrel model is a multiplicative model component.

The model is described at [1] .

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

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

mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.nH thawed 0 -1e+06 1e+06 10^22 atoms / cm^2 mdl.He frozen 1 0 1e+38 mdl.C frozen 1 0 1e+38 mdl.N frozen 1 0 1e+38 mdl.O frozen 1 0 1e+38 mdl.Ne frozen 1 0 1e+38 mdl.Na frozen 1 0 1e+38 mdl.Mg frozen 1 0 1e+38 mdl.Al frozen 1 0 1e+38 mdl.Si frozen 1 0 1e+38 mdl.S frozen 1 0 1e+38 mdl.Cl frozen 1 0 1e+38 mdl.Ar frozen 1 0 1e+38 mdl.Ca frozen 1 0 1e+38 mdl.Cr frozen 1 0 1e+38 mdl.Fe frozen 1 0 1e+38 mdl.Co frozen 1 0 1e+38 mdl.Ni frozen 1 0 1e+38 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 0.5 0 1 mdl.N_dep frozen 1 0 1 mdl.O_dep frozen 0.6 0 1 mdl.Ne_dep frozen 1 0 1 mdl.Na_dep frozen 0.25 0 1 mdl.Mg_dep frozen 0.2 0 1 mdl.Al_dep frozen 0.02 0 1 mdl.Si_dep frozen 0.1 0 1 mdl.S_dep frozen 0.6 0 1 mdl.Cl_dep frozen 0.5 0 1 mdl.Ar_dep frozen 1 0 1 mdl.Ca_dep frozen 0.003 0 1 mdl.Cr_dep frozen 0.03 0 1 mdl.Fe_dep frozen 0.3 0 1 mdl.Co_dep frozen 0.05 0 1 mdl.Ni_dep frozen 0.04 0 1 mdl.redshift frozen 0 -1 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

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

Changes in CIAO

The default nH parameter value has changed from 1.0 to 0.0 to match XSPEC.

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

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

December 2023