Super-exponential cutoff absorption model

Absorption model

M(E) = exp ( −(E/Ec)α )

useful for fitting gamma-ray spectra of pulsars (see eg Nel & de Jager 1995).

par1 = Ecut, characteristic energy (keV)
par2 = alpha, exponent index

Caveat : the absorption for an energy bin is calculated as the arithmetic mean of the function value at the start and end energies of the bin. If the energy bins are large this can be inaccurate and the xspec energies command should be used to define a finer energy grid on which to calculate the model.

The source code file required is superExpCutoff.cxx with the parameter information in superExpCutoff_lmodel.dat. This model works with xspec v12 but does not work with v11.


Keith Arnaud, Lab. for High Energy Astrophysics, NASA/Goddard Space Flight Center

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Last modified: Thursday, 04-Sep-2008 15:47:16 EDT