Acceleration of galactic cosmic rays by supernova shocks in the interstellar medium

Shocks from supernovae propagating through the galaxy will reaccelerate ambient cosmic rays by a first-order Fermi mechanism. The process is energetically important if most of the volume of the interstellar medium is in the low density coronal phase and supernova blast waves can propagate for more than 100 pc before cooling. Using the standard leaky box model and simple treatments of injection, escape, ionization, radiation and spallation losses, steady state spectra are computed for protons, electrons and light, medium and heavy nuclei. Derived spectra are in good agreement with observations, with the most sensitive test of the model provided by the dependence of grammage on rigidity