Blast waves with cosmic-ray pressure

Abstract

The effect of efficient cosmic-ray acceleration on the structure ofblast waves and of driven waves created by supernova explosions isinvestigated. The solutions for the structures are used in predictingthe pion-decay gamma-ray fluxes from supernovae and supernova remnants.The solutions are parameterized using w, which is the ratio of therelativistic cosmic-ray pressure to the total pressure in the shockfront. For blast waves from a point explosion in a uniform medium, thecosmic rays are found to dominate the pressure near r = 0 if w isgreater than 0. The solutions reveal that, if w is small, the ratio ofcosmic-ray energy to the total energy in the blast wave is several timesw. The solutions are used in making specific prediction of thepion-decay gamma-ray flux from a blast wave as a function of w. If w islarge, the predicted fluxes from supernova remnants approximate thecurrent observational limits. It is also pointed out that cosmic raysmay limit the compression in the radiative shock waves of supernovaremnants.