2002ApJ...569L..61Q

It has been proposed that very massive stars (VMSs) dominated heavy-element production until a ``metallicity'' threshold corresponding to [Fe/H]~-3 was reached. This results in a prompt (P) inventory of elements, the abundances of which were determined from observations of Galactic halo stars with [Fe/H]~-3. We calculate Ω<sub>P</sub>(E) from the P inventory for a large number of elements in the intergalactic medium (IGM). Using the available data on Ω(E<sub>ion</sub>) for C IV, O VI, and Si IV in Lyα systems, we find that the ionization fractions calculated from Ω(E<sub>ion</sub>)/Ω<sub>P</sub>(E) are, within reasonable uncertainties, compatible with the values estimated from ionization models for Lyα systems. This agreement appears to hold from z∼0.09 to ∼4.6, indicating that the bulk of the baryonic matter remains dispersed with a fixed chemical composition. We conclude that the P inventory was established in the epoch prior to z∼4.6. The dispersal of processed baryonic matter to the general IGM is considered to be the result of energetic VMS explosions that disrupted baryonic aggregates until the ``metallicity'' threshold was reached to permit normal astration. The formation of most galaxies is considered to have occurred subsequent to the achievement of this metallicity threshold in the IGM.