4.1.19. Gaus: gaussian line model¶
The Gaussian line model is the simplest model for a broadened emission line.
The spectrum is given by:
where is the photon energy in keV, the photon flux in units of ph , is the average line energy of the spectral line (in keV) and is the line normalisation (in units of ph ). The total line flux is simply given by . Further is the Gaussian width, which is related to the full width at half maximum by or approximately .
To ease the use for dispersive spectrometers (gratings) there is an option to define the wavelength instead of the energy as the basic parameter. The parameter type determines which case applies: type=0 (default) corresponding to energy, type=1 corresponding to wavelength units.
Warning
Do not confuse with when interpreting your fit results with other data.
Warning
When changing from energy to wavelength units, take care about the frozen/thawn status of the line centroid and FWHM.
Warning
You need to do a calc
or fit
command to get an update
of the wavelength (for type=0) or energy (type=1).
The parameters of the model are:
norm
: Normalisation , in units of
ph . Default value: 1.e
: The line energy in keV. Default value: 6.4 keV.fwhm
: The line , in keV.type
: The type: 0 for energy units, 1 for wavelength units.w
: The line wavelength in Å. Default value: 20 Å.awid
: The line , in Å.Recommended citation: Gauss (1809).