Model to aid estimating fluxes and errors

This convolution model can be used with any other combination of models in order to estimate the flux and errors. The first two parameters are the minimum and maximum energy (in keV) over which the flux is calculated. These parameters must be frozen. The third parameter is the log (base 10) of the flux in erg/cm^2/s. It is important to ensure that the energy range over which the model is calculated (which is determined by the response matrix in use) covers the energy range for which the flux is calculated. To use this model place the cflux component immediately in front of the component(s) for which you want to estimate the flux and fix the normalization parameter of one of the additive components. Now fit and use the error command as usual on the flux parameter. For instance, suppose the model is :

phabs*(pow + gauss)

then
cflux*phabs*(pow + gauss)

with the normalizaton of the power-law model fixed gives the flux and error on the entire model.

phabs*cflux*(pow + gauss)

again with the normalization of the power-law fixed gives the unabsorbed flux and error. Finally,

phabs*(pow + cflux*gauss)

with the normalizaton of the gaussian fixed gives the flux and error on the gaussian component.

The source code file required is cflux.cxx with the parameter information in cflux_lmodel.dat. Note that this model requires xspec v12 - it does not work in v11.


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

Xspec Xspec Home Page


HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public

Last modified: Thursday, 21-Aug-2008 10:39:45 EDT