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20 April 2024
 
  » arxiv » astro-ph/0109400

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Did Very Massive Stars Pre-enrich and Reionize the Universe?
S. Peng Oh ; Kenneth M. Nollett ; Piero Madau ; G.J. Wasserburg ;
Date 23 Sep 2001
Subject astro-ph
Affiliation Caltech, UC Santa Cruz
AbstractRecent studies of heavy r-process elements in low [Fe/H] halo stars have suggested that an initial population of metal-free very massive stars (VMSs) may be required to provide early Fe enrichment without coproducing heavy r nuclei. We find similar abundance trends in alpha-elements (which should be copiously produced by VMSs), but not in other elements such as carbon (which should not), in agreement with this hypothesis. We then combine the corresponding level of prompt initial enrichment with models of VMS nucleosynthetic yields and spectra to estimate the corresponding ionizing fluxes. The result suggests that there may have been enough VMS activity to reionize the universe. The unusually hard spectrum of VMSs would imply a different reionization history from canonical models. HeII could have been reionized at high redshift, only to recombine as a subsequent generation of stars formed with a ``normal’’ initial mass function.
Source arXiv, astro-ph/0109400
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