An assessment of models for the γ-ray flux from the Galactic plane

Abstract

An assessment is made of five models for the production of Galactic gamma rays, all of which involve the interaction of cosmic ray protons with neutral hydrogen. Conflict with either the gamma ray or radio data is found in four cases. The remaining model, in which the intensity of cosmic rays of energy of a few GeV is correlated with the matter distribution in the Galaxy, gives rough agreement with the experimental data at present available but it does not conform with the idea that cosmic rays should originate in young Galactic objects. A completely satisfactory model has yet to be found.