srcut: synchrotron spectrum, cutoff power law

srcut describes the synchrotron spectrum from an exponentially cut off power-law distribution of electrons in a homogeneous magnetic field. This spectrum is itself a power-law, rolling off more slowly than exponential in photon energies. Though more realistic than a power-law, it is highly oversimplified, but does give the maximally curved physically plausible spectrum and can be used to set limits on maximum accelerated-electron energies even in remnants whose X-rays are thermal. See Reynolds & Keohane (1999) and Reynolds (1998). Note that the radio spectral index and flux can be obtained from Green's Catalogue for galactic SNRs.

par1 alpha: radio spectral index
par2 break Hz: approximately the frequency at which the flux has dropped by a factor of 10 from a straight power law.
norm 1 GHz flux (Jy)