Cosmological Impact of Population III Binaries
  We present the results of the stellar feedback from Pop III binaries by
employing improved, more realistic Pop III evolutionary stellar models. To
facilitate a meaningful comparison, we consider a fixed mass of 60 solar masses
(Msun) incorporated in Pop III stars, either contained in a single star, or
split up in binary stars of 30 Msun each or an asymmetric case of one 45 Msun
and one 15 Msun star. Whereas the sizes of the resulting HII regions are
comparable across all cases, the HeIII regions around binary stars are
significantly smaller than that of the single star. Consequently, the He$^{+}$
1640 angstrom recombination line is expected to become much weaker. Supernova
feedback exhibits great variety due to the uncertainty in possible explosion
pathways. If at least one of the component stars dies as a hypernova about ten
times more energetic than conventional core-collapse supernovae, the gas inside
the host minihalo is effectively blown out, chemically enriching the
intergalactic medium (IGM) to an average metallicity of $10^{-4}-10^{-3}$ solar
metallicity (Zsun), out to $\sim 2$ kpc. The single star, however, is more
likely to collapse into a black hole, accompanied by at most very weak
explosions. The effectiveness of early chemical enrichment would thus be
significantly reduced, in difference from the lower mass binary stars, where at
least one component is likely to contribute to heavy element production and
dispersal. Important new feedback physics is also introduced if close binaries
can form high-mass x-ray binaries, leading to the pre-heating and -ionization
of the IGM beyond the extent of the stellar HII regions.
