We review the properties of galaxies at z > 5, specifically those selected using the Lyman break technique. We show that these sources are typically young starbursts with relatively dust-free star formation regions. They are resolved on scales of 1 – 2 kpc, sometimes with multiple components seperated by a few kpc. They are smaller than z = 3 Lyman break galaxies (LBGs). As a population, they show no evidence of hosting AGN, obscured or otherwise. Approximately half of the photometrically-selected LBGs at IAB ~ 26 show Ly emission with luminosities of 1042–43 erg s–1. The comoving number density of Lyman break galaxies at z > 5 with M AB(1700?) < –21 is a factor ~ 3 lower than that for similar LBGs at z = 3 – 4. The integrated UV emission from z ~ 5 LBGs brighter than MAB(1700?) < –17.5 is sufficient to ionize their local volume. A similar population at much higher redshift would not be able to keep its local volume ionized.
展开▼