AbsorptionGaussian

class sherpa.astro.optical.AbsorptionGaussian(name='absorptiongaussian')[source]

Bases: sherpa.models.model.RegriddableModel1D

Gaussian function for modeling absorption (equivalent width).

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.

fwhm

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

pos

The center of the gaussian, in Angstroms.

ewidth

The equivalent width of the model.

limit

The model is only evaluated for points that lie within limit sigma of pos. It is a hidden parameter, with a value fixed at 4.

Notes

The functional form of the model for points is:

f(x) = 1 - ampl * exp(-0.5 * ((x - pos)/sigma)^2)

ampl = ewidth / sigma / 2.50662828

sigma = pos * fwhm / (2.354820044 * c)

and for integrated data sets the low-edge of the grid is used. The calculation is only done for those points that are in the range:

|x - pos| < limit * sigma

Outside this range the model is set to 1.

Attributes Summary

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Summary

apply(outer, *otherargs, **otherkwargs)
calc(p, x[, xhi]) Evaluate the model on a grid.
get_center()
guess(dep, *args, **kwargs) Set an initial guess for the parameter values.
regrid(*arrays)
reset()
set_center(*args, **kwargs)
startup() Called before a model may be evaluated multiple times.
teardown() Called after a model may be evaluated multiple times.

Attributes Documentation

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Documentation

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

Evaluate the model on a grid.

Parameters:
  • p (sequence of numbers) – The parameter values to use. The order matches the pars field.
  • *args – The model grid. The values can be scalar or arrays, and the number depends on the dimensionality of the model and whether it is being evaluated over an integrated grid or at a point (or points).
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.

regrid(*arrays)
reset()
set_center(*args, **kwargs)
startup()

Called before a model may be evaluated multiple times.

See also

teardown()

teardown()

Called after a model may be evaluated multiple times.

See also

setup()