bknpower, zbknpower: broken power law

bknpower is a broken power law and zbknpower a redshifted variant.

$$A(E) = \left\{ \begin{array}{ll} K E^{-\Gamma_1} & \mbox{if... ...Gamma_2} & \mbox{if $E > E_{break}$} \\ \end{array} \right.$$

where:

par1 = $\Gamma_1$	power law photon index for $E < E_{break}$
par2 = $E_{break}$	break point for the energy in keV
par3 = $\Gamma_2$	power law photon index for $E > E_{break}$
norm = K	photons/keV/cm$^2$/s at 1 keV

The formula and parameters for the redshifted variant are:

$$A(E) = \left\{ \begin{array}{ll} K [E(1+z)]^{-\Gamma_1} & \... ...} & \mbox{if $[E(1+z)] > E_{break}$} \\ \end{array} \right.$$

where:

par1 = $\Gamma_1$	power law photon index for $E < E_{break}$
par2 = $E_{break}$	break point for the energy in keV
par3 = $\Gamma_2$	power law photon index for $E > E_{break}$
par4 = $z$	redshift
norm = K	photons/keV/cm$^2$/s 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 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.