A possible cosmic ray primary particle energy spectrum above 104 GeV and its astrophysical implications

A primary cosmic ray particle energy specturm of Galactic origin with a sharp cut-off at an energy per nucleon of 3 × 10⁴ GeV for protons and 5 × 10⁴ GeV for heavier particles and extending only upto energies ～ 10¹⁵ eV is deduced in part from the observed cosmic ray phenomena at the highest energies. It appears that the cut off is not due to the magnetic rigidity of the particles in the Galaxy but due to a cut off in or near the sources themselves. In particular, it is pointed out that Fermi type of acceleration is unlikely to be important in the production of energetic cosmic ray particles in the Galaxy. A pedestal in the energy spectrum from an extra Galactic component upto a maximum energy per nucleon ～ 10⁷ GeV with an upper limit of total energies ～ 10¹⁸ eV has been added.