Cosmological cosmic rays and the observed6Li plateau in metal-poor halo stars

Emmanuel Rollinde, Elisabeth Vangioni, Keith Olive

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

Very recent observations of the 6Li isotope in halo stars reveal a 6Li plateau about 1000 times above the predicted big bang nucleosynthesis abundance. We calculate the evolution of 6Li versus redshift generated from an initial burst of cosmological cosmic rays (CCRs) up to the formation of the Galaxy. We show that the pre-Galactic production of the 6Li isotope can account for the 6Li plateau observed in metal-poor halo stars without additional over-production of 7Li. The derived relation between the amplitude of the CCR energy spectra and the redshift of the initial CCR production puts constraints on the physics and history of the objects, such as Population III stars, responsible for these early cosmic rays. Consequently, we consider the evolution of 6Li in the Galaxy. Since 6Li is also produced in Galactic cosmic-ray nucleosynthesis, we argue that halo stars with metallicities between [Fe/H] = -2 and -1 must be somewhat depleted in 6Li.

Original languageEnglish (US)
Pages (from-to)666-673
Number of pages8
JournalAstrophysical Journal
Volume627
Issue number2 I
DOIs
StatePublished - Jul 10 2005

Keywords

  • Cosmic rays
  • Cosmology: theory
  • Early universe nuclear reactions, nucleosynthesis, abundances
  • Stars: abundances

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