Galactic cosmic rays from superbubbles and the abundances of lithium, beryllium, and boron

In this article we study the Galactic evolution of the LiBeB elements within the framework of a detailed model of the chemical evolution of the Galaxy that includes Galactic cosmic-ray (GCR) nucleosynthesis by particles accelerated in superbubbles. The chemical composition of the superbubble consists of varying proportions of interstellar medium (ISM) and freshly supernova-synthesized material. The observational trends of (LiBeB)-Li-6 evolution are nicely reproduced by models in which GCRs come from a mixture of 25% supernova material with 75% ISM, except for Li-6, for which perhaps an extra source is required at low metallicities. To account for Li-7 evolution, several additional sources have been considered (neutrino-induced nucleosynthesis, nova outbursts, and C stars). The model fulfills the energetic requirements for GCR acceleration.