Examination of the model of supernovae origin of galactic cosmic rays by the theory of nucleosynthesis and by observations of TeV gamma-ray emission

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Supernova remnants (SNRs) are widely believed to be a major source of galactic cosmic rays (GCRs) from the general arguments on energetics, shock acceleration mechanisms, and the chemical composition of the source of GCR. In this project, we examined this scenario both theoretically and experimentally.It is found that the galactic cosmic ray source composition is reproduced within a factor of 1.6 as a mixture of fresh ejecta of Type Ia and Type II supernovae, the interstellar matter which is swept up by the ejecta, and Wolf-Rayet stellar wind material. The best mixing ratio of the four source materials are determined on the basis of the recent nucleosynthetic models of supernovae. As a bonus, the frequency of occurrence of SNIa relative to SNII and acceleration time of the GCRs after SNe explosions are estimated with the best mixing ratios to be 〜0.43 and 〜1000 y respectively.We observed the shell type SNR RX J1713.7-3946 with CANGAROO 3.8 m atmospheric Cerenkov telescope and obtained evidence for TeV gamma-ray emission from the NW rim of the remnant with 〜5.6 statistical significance. The data indicate that the emitting region is much broader than the point spreading function of the telescope. The extent of the emission is consistent with that of hard X-rays observed by ASCA. This TeV gamma-ray emission can be attributed to the Inverse Compton scattering of the Cosmic Microwave Background radiation by shock accelerated ultra-relativistic electrons. Under this assumption, a rather low magnetic field of 〜11 microgauss is deduced for the remnant.