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powerlaw, zpowerlw: power law photon spectrum

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

$\displaystyle A(E) = K E^{-\alpha} $

where:

par1 $\alpha $, photon index of power law (dimensionless)
norm $K$, photons/keV/cm$^2$/s at 1 keV

For zpowerlw the formula and corresponding parameters are:

$\displaystyle A(E) = K [E(1+z)]^{-\alpha} $

where:

par1 $\alpha $, photon index of power law (dimensionless)
par2 $z$, 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.

next up previous contents
Next: pshock, vpshock, vvpshock, bpshock, Up: Additive Model Components Previous: posm: positronium continuum   Contents