Star Formation and Metal Production as a Function of Redshift: The Role of the Multiphase ISM

摘要

We present models of the cosmological star formation and metal production history of (proto)galaxies with varying axis ratios. More massive and/or roughly spherical systems reach the threshold metallicity for the transition to a multiphase interstellar medium earlier than less massive and/or more flattened systems. Therefore, more flattened and/or lower mass systems start to form stars actively at smaller redshifts. A natural explanation for this result is found in the overall robustness of the interstellar medium against complete expulsion (blow-away) at high total masses and in the prevention of metal enrichment in the outer regions by axial outflow along the symmetry axis of a nonspherical protogalaxy (blow-out).