STAR FORMATION DURING GALAXY FORMATION

Young galaxies are clumpy, gas-rich, and highly turbulent. Star formation appears to occur by gravitational instabilities in galactic disks. The high dispersion makes the clumps massive and the disks thick. The star formation rate should be comparable to the gas accretion rate of the whole galaxy, because star formation is usually rapid and the gas would be depleted quickly otherwise. The empirical laws for star formation found locally hold at redshifts around 2, although the molecular gas consumption time appears to be smaller, and mergers appear to form stars with a slightly higher efficiency than the majority of disk galaxies.