Atten

class sherpa.astro.models.Atten(name='atten')

Bases: sherpa.models.model.ArithmeticModel

Model the attenuation by the Inter-Stellar Medium (ISM).

This model calculates the transmission of the interstellar medium using the description of the ISM absorption of [1]. It includes neutral He autoionization features. Between 1.2398 and 43.655 Angstroms (i.e. in the 0.28-10 keV range) the model also accounts for metals as described in [2]. It should only be used when the independent axis has units of Angstroms.

hcol

The column density of HI in atoms cm^-2.

heiRatio

The ratio of the HeI to HI column densities.

heiiRatio

The ratio of the HeII to HI column densities.

Notes

The code uses the best available photoionization cross-sections to date from the atomic data literature and combines them in an arbitrary mixture of the three ionic species: HI, HeI, and HeII.

This model provided courtesy of Pat Jelinsky.

The grid version is evaluated by numerically intgerating the function over each bin using a non-adaptive Gauss-Kronrod scheme suited for smooth functions [3], falling over to a simple trapezoid scheme if this fails.

References

[1]	Rumph, Bowyer, & Vennes 1994, AJ 107, 2108 http://adsabs.harvard.edu/abs/1994AJ....107.2108R

[2]	Morrison & McCammon 1983, ApJ 270, 119 http://adsabs.harvard.edu/abs/1983ApJ...270..119M

[3]	https://www.gnu.org/software/gsl/manual/html_node/QNG-non_002dadaptive-Gauss_002dKronrod-integration.html

Attributes Summary

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Summary

apply(outer, \*otherargs, \*\*otherkwargs)
calc(pars, xlo, \*args, \*\*kwargs)
get_center()
guess(dep, \*args, \*\*kwargs)	Set an initial guess for the parameter values.
reset()
set_center(\*args, \*\*kwargs)
startup()
teardown()

Attributes Documentation

thawedparhardmaxes

thawedparhardmins

thawedparmaxes

thawedparmins

thawedpars

Methods Documentation

apply(outer, *otherargs, **otherkwargs)

calc(pars, xlo, *args, **kwargs)

get_center()

guess(dep, *args, **kwargs)

Set an initial guess for the parameter values.

Attempt to set the parameter values, and ranges, for the model to match the data values. This is intended as a rough guess, so it is expected that the model is only evaluated a small number of times, if at all.

reset()

set_center(*args, **kwargs)

startup()

teardown()