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            powerlaw, zpowerlw: power law photon spectrum

powerlaw is a simple photon power law. The zpowerlw variant computes a redshifted spectrum.

par1 = a

photon index of power law (dimensionless)

norm= K

photons keV1cm2s1 at 1 keV

 

For zpowerlw the formula and corresponding parameters are:

 

where :

par1= a

photon index of power law (dimensionless)

par2= z

Redshift

norm= K

photons keV1cm2s1 at 1 keV

 

If POW_EMIN and POW_EMAX have been defined by the xset command then the norm becomes the flux in units of 10-12 ergs cm-2 s-1 over the energy range (POW_EMIN, POW_EMAX) keV unless POW_EMIN = POW_EMAX in which case the norm becomes the flux density in micro-Jansky at POW_EMIN keV. In these cases it is important that POW_EMIN and POW_EMAX lie within the energy range on which the model is being evaluated.

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Next: Pshock Up: Additive Model Components Previous: Posm