Cosmic Ray Variations from Supernovae and Galaxy Core Flare-ups.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmic Ray Variations from Supernovae and Galaxy Core Flare-ups. Rosen, Stephen ; Milford, S. N. Abstract Approximate constancy of the primary cosmic ray intensity over periods of 10~-10~ yr and slight variations over shorter times appears from study of meteoritic nuclide ratios. Upper limits to the measured cosmic ray anisotropy indicate that approximate isotropy prevails. The calculations here assume that slight anisotropy and secular variations of cosmic rays could be attributed to supernovae or galaxy core flare-ups. It is also assumed that the (constant) mean time between supernovae is T8n=102~+ yr in the galactic disk and over the Galaxy lifetime. Diffusion solutions for point instantaneous isotropic sources in an unbounded medium predict small secular variations and anisotropy. Combining these predictions with Tsn and limits on cosmic ray variations gives estimates for the age and distance of a possible supernova event. For example, a supernova 102~104 light years away which occurred 10~-10~ yr ago would be consistent with supernova frequency and with cosmic ray time and space variations. Estimates of Cygnus Loop parameters (Minkowski, R., Rev. Mod. Phys. 30, 1048, 1958) suggest that it could be an example which may meet the requirements of these calculations. A flare-up at the center of a galaxy possessing a spherical halo is considered as a source of cosmic ray variations. This model provides estimates of the age and size of the outburst, and of the magnitude of the diffusion constants of the cosmic rays inside and outside the spherical boundary. The predictions of an infinite medium model (Charakhch'yan, A. N., and Charakhch'yan, T. N., Geom. and Aeron. 4, 509, 1964) are compared with these results. Publication: The Astronomical Journal Pub Date: 1966 DOI: 10.1086/110154 Bibcode: 1966AJ.....71S.395R full text sources ADS |