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

Observations with the Compton Gamma Ray Observatory of gamma rays above 100 MeV from the Large and Small Magellanic Clouds open up the possibility 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 interaction of cosmic rays with the gas in the mc, shows clearly that this model is not tenable: an upper limit of 11% can be put on the contribution of such extragalactic particles to the observed flux.