Supernova remnants and the origin of the cosmic radiation: II. Spectral variations in space and time

The model described by us earlier (Erlykin and Wolfendale 2001aJ. Phys. CI Nucl. Part. Phys, 27 941), which involves Monte Carlo calculations for cosm ic rays accelerated by supernova remnants in the interstellar medium, has b een used to predict Galactic cosmic ray energy spectra as a function of spa ce and time. Moderate variations of cosmic ray characteristics connected wi th the random spacetime distribution of supernovae are found to be accompan ied by much stronger changes caused by explosions of nearby and recent supe rnovae. The spatial variations have been compared with results from gamma ray astro nomy which relate to possible small variations in spectral shape for the av erage cosmic ray proton intensity in the energy range 3-100 GeV out to dist ances of some 100s of pc from the Earth (Fatoohi ct nl 1995 J. Phys. GI Nuc l. Part. Phys. 21 679). Similarly, comparison has been made with results fr om radio-astronomy, which relate to the electron component. There is found to be no inconsistency with the model predictions in either case. The predicted temporal changes in the cosmic ray intensity at Earth in the range 10-50 GeV, appropriate to cosmogenic nucleus measurements, are, again , not inconsistent with those observed tan upper limit of a few 10s of per cent, with the value depending on the cosmogenic nucleus under study). The amplitude of the anisotropy in arrival directions of cosmic rays predic ted by the model is of the order of that observed (typically 1% at 1 PeV) f or the situation where there has been a local, recent supernova.