AbsorptionVoigt

class sherpa.astro.optical.AbsorptionVoigt(name='absorptionvoigt')

Bases: sherpa.models.model.ArithmeticModel

Voigt function for modeling absorption (equivalent width).

This model uses an AbsorptionGaussian component to model the core of the profile and an AbsorptionLorentz component to model the wings of the absorption feature. This model is intended to be used to modify another model (e.g. by multiplying the two together). It is for use when the independent axis is in Angstroms.

center

The center of the profile, in Angstroms.

ew

The equivalent width of the profile. The ewidth parameter of the Gaussian and Lorentz sub-components is set to half this value.

fwhm

The full-width half-maximum of the model in km/s.

lg

The fwhm parameters of the Gaussian and Lorentz components are set based on the fwhm and lg values: the Gaussian component has its fwhm parameter set equal to fwhm, and the Lorentz component has its fwhm parameter set to lg * fwhm.

See also

AbsorptionEdge, AbsorptionGaussian, AbsorptionVoigt, EmissionLorentz, OpticalGaussian

Notes

The Voigt function is approximated by the sum of a Gaussian and a Lorentzian profile ([1]), which works best when the ratio between the FWHM of the Gaussian and Lorentzian sub-components is near unity. The flux value is always kept evenly divided in between each sub-component. The FWHM of each sub-component is related to that of the other sub-component via the lg parameter.

References

[1]	Lang, Astrophysical Formulae, 1980, 2nd ed., page 220

Attributes Summary

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Summary

apply(outer, \*otherargs, \*\*otherkwargs)
calc(p, x[, xhi])
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(p, x, xhi=None, **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()