From a NASA website:
"Galactic cosmic rays (GCRs) come from outside the solar system but generally from within our Milky Way galaxy. GCRs are atomic nuclei from which all of the surrounding electrons have been stripped away during their high-speed passage through the galaxy. They have probably been accelerated within the last few million years, and have traveled many times across the galaxy, trapped by the galactic magnetic field. GCRs have been accelerated to nearly the speed of light, probably by supernova remnants. As they travel through the very thin gas of interstellar space, some of the GCRs interact and emit gamma rays, which is how we know that they pass through the Milky Way and other galaxies. "
Interesting, it was quite a while ago that I was in physics and quite a while ago before that that the books we used were written. Other sources I'd seen put Gamma waves at the top of the EMR. That's why I hedged my statement with "when I took physics". Thanks.