COSMIC-RAYS OF THE HIGHEST ENERGIES .3. THE NATURE OF THE CANDIDATE DISCRETE SOURCES

A first attempt has been made to identify the galactic 'sources' of cosmic rays above 10(19) eV, which are presumed to be responsible for the clusters described in our previous papers and a significant fraction of the other ultra-high-energy particles recorded by the extensive air shower arrays. Of a number of potential sources examined, variable stars gave the strongest correlation with the cosmic ray arrival directions. In view of the absence of a reasonable acceleration mechanism for such sources it is safest to conclude that the sources (if indeed the detected clusters are due to sources) may well have a similar distribution in the sky to the variable stars in question. One such possibility is that pulsars are responsible, although again there are problems with the theory. Nonetheless this possibility has been examined in depth-with the result that pulsars are considered to be possible sources of the galactic particles at the very high energies in question.