Spallogenic Light Elements and Cosmic-Ray Origin

Using a Monte Carlo code which incorporates hitherto ignored effects, the delayed mixing into the ISM of the nucleosynthetic yields of supernovae and the relationship between these yields and the supernova ejecta kinetic energy (including events with very large ejecta energies, e.g. collapsars/hypernovae), we tested the viability of the three recent evolutionary models for the origin of the spallogenic light elements, specifically Be. We find that the CRI, in which the cosmic rays are accelerated out of an ISM which is increasingly metal poor at early times, significantly under-predicts the measured Be abundance at the lowest [Fe/H], the increase in [O/Fe] with decreasing [Fe/H] indicated by recent data notwithstanding. We also find that the CRS, in which cosmic rays with composition similar to that of the current epoch cosmic rays are accelerated out of fresh supernova ejecta and thus maintain a constant metallicity at all epochs, can account for the measured Be abundances with an acceleration efficiency that is in good agreement with the current epoch cosmic-ray data. In addition, we show that the LECR, in which a postulated low energy component also accelerated out of fresh ejecta coexists with the CRI cosmic rays, can account for the observations as well, except that the required acceleration efficiency becomes prohibitively large for some of the parameters that have been previously assumed for this as-yet undetected cosmic-ray component.