Their highest-energy sources are concentrated in the northern galactic latitudes around the Virgo supercluster.  
They drop in intensity in a Forbush decrease following a coronal mass ejection.  Their spectral index goes from about 2.7 to 3 at the so-called knee, and it is thought that above the knee they consist predominantly of heavy nuclei.  One model for their production is the Fermi acceleration mechanism operating in shocks in supernova remnants.  Their highest-energy sources are concentrated in the northern galactic latitudes around the Virgo supercluster.  First detected by Hess during a balloon ascent, FTP name these particles with energies up to 1020 ("ten to the twenty") electron-volts which can originate in the Sun, the Milky Way, or from extra-galactic sources.
They drop in intensity in a Forbush decrease following a coronal mass ejection.  
cosmic rays