GAMMA-RAYS FROM THE MAGELLANIC CLOUDS AND THE ORIGIN OF COSMIC-RAYS

Observations with the Compton Gamma Ray Observatory of gamma rays abov e 100 MeV from the Large and Small Magellanic Clouds open up the possi bility of testing various hypotheses for the origin of cosmic rays. In the present work we examine the possibility that the cosmic rays seen at the earth are of extragalactic origin. The analysis, which relates to a determination of the flux of gamma rays arising from the interac tion of cosmic rays with the gas in the mc, shows clearly that this mo del is not tenable: an upper limit of 11% can be put on the contributi on of such extragalactic particles to the observed flux.