Beryllium and boron constraints on an early galactic bright phase

Brian D. Fields, David N. Schramm, James W. Truran

Research output: Contribution to journalArticlepeer-review


The recent observations of Be and B in metal-deficient halo dwarfs are used to constrain a "bright phase" of enhanced cosmic-ray flux in the early Galaxy. Assuming that this Be and B arises from cosmic-ray spallation in the early Galaxy, limits are placed on the intensity of the early (Population II) cosmic-ray flux relative to the present (Population I) flux. A simple estimate of bounds on the flux ratio is 1 ≲ ΦPop IIPop I ≲ 40. This upper bound would restrict galaxies like our own from producing neutrino fluxes that would be detectable in any currently proposed detectors. It is found that the relative enhancement of the early flux varies inversely with the relative time of enhancement. It is noted that associated gamma-ray production via pp → π0pp may be a significant contribution to the gamma-ray background above 100 MeV.

Original languageEnglish (US)
Pages (from-to)559-566
Number of pages8
JournalAstrophysical Journal
Issue number2
StatePublished - Mar 10 1993
Externally publishedYes


  • Cosmic rays
  • Elementary particles
  • Nuclear reactions, nucleosynthesis, abundances
  • Stars: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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