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M. L. Norman, P. Paschos, B. W. O'Shea (UCSD)
We report on hydrodynamical cosmological simulations which track the evolution of metals produced by massive Pop III stars at high redshifts (z~20) to z=3 where they can in principle be detected in QSO absorption line systems. The simulations include a parameterized model of star formation and feedback, metal enrichment, a time-evolving UV background, and radiative heating and cooling. Two metallicity fields are tracked: the Pop III metals, which are initialized at z=15, and the Pop II metals produced by protogalaxies continuously at 15>z>3. Synthetic CIV and HI Lyman alpha absorption line spectra are produced and analyzed. We find that most Pop III metals are incorporated into forming galaxies, where their absorption line signatures are overwhelmed by Pop II metals. However, some Pop III metals remain in isolated bubbles in void regions. Because void gas is substantially cooler, these show up as very narrow lines (b~5 km/s) in the CIV Doppler parameter distribution function, which is otherwise dominated by broader lines (b~10-20 km/s) from galactic CIV. The key uncertainty is the mass of carbon ejected by each Pop III supernova. We analyze two likely scenarios: pair instability supernovae and Type II supernovae. This work is supported by NSF grant AST-0307690 and NRAC supercomputer resource allocation MCA098020S.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.