EmissionGaussian¶

class sherpa.astro.optical.EmissionGaussian(name='emissiongaussian')[source]¶

Bases: sherpa.models.model.ArithmeticModel

Gaussian function for modeling emission.

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.

flux¶: The normalisation of the gaussian.

skew¶: The skew of the gaussian.

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

Notes

The functional form of the model for points is:

f(x) = flux * exp(-0.5 * d(x)^2) / s2   if skew = 1

     = 2 * flux * exp(-0.5 * d2(x)^2) / (s2 * (1 + skew))

                                        otherwise

d(x) = (x - pos) / s

d2(x) = d(x)                  if x <= pos

      = d(x) / skew           otherwise

s2 = 2.50662828 * s

s = pos * fwhm / (2.9979e5 * 2.354820044)

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 0.

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)[source]¶

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()¶