Late Reionization by Supernova-driven Winds

A model is presented in which supernova-driven winds from early galaxies reionize the intergalactic medium by z = 5. This scenario can explain the observed absence of a Gunn-Peterson trough in the spectra of high- redshift quasars providing that the bulk of these early galaxies are quite small, no more massive than about 108 Msun. It also predicts that most of the IGM was enriched to at least 10% of current metal content by z = 5 and perhaps as early as z = 15. The existence of such early minigalaxies violated no spectral constraints and is consistent with a pure CDM model with b ≤ 2. Since the final radius of a typical ionized bubble is only around 100 kpc, the induced modification of the galaxy autocorrelation function is negligible, as is the induced angular smoothing of the CMBR. Some of the gas swept up by shells may be observable as pressure supported Lyman-alpha forest clouds.