Light-element evolution and cosmic-ray energetics

Reuven Ramaty, Sean T. Scully, Richard E. Lingenfelter, Benzion Kozlovsky

Research output: Contribution to journalArticlepeer-review

Abstract

Using cosmic-ray energetics as a discriminator, we investigate the viability of evolutionary models for the light elements Li, Be, and B (LiBeB). We find that models in which the cosmic rays are accelerated mainly out of the average interstellar medium which is increasingly metal-poor at early times significantly underpredict the measured Be abundance of the early Galaxy, the possible increase in [O/Fe] with decreasing [Fe/H] indicated by some recent data notwithstanding. On the other hand, if the cosmic-ray metals are accelerated primarily out of supernova ejecta-enriched superbubbles, such that the cosmic-ray source composition as a function of [Fe/H] remains similar to that of the current epoch, the measured Be abundances are consistent with a cosmic-ray acceleration efficiency that is in very good agreement with the current epoch data. This model requires the incorporation of neutrino-produced 11B. We show that, even though the production histories of the cosmic-ray-produced B and Be and the neutrino-produced 11B are different, B/Be can remain essentially constant as a function of [Fe/H]. We also find that neither the above cosmic-ray origin models nor a model employing low-energy cosmic rays originating from the supernovae of only very massive progenitors can account for the 6Li data at values of [Fe/H] below -2.

Original languageEnglish
Pages (from-to)747-756
Number of pages10
JournalAstrophysical Journal
Volume534
Issue number2 PART 1
DOIs
StatePublished - 10 May 2000

Keywords

  • Cosmic rays
  • Galaxy: evolution
  • Supernovae: general

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