Feedback From the First Supernovae in Protogalaxies:The Fate of the Generated Metals

Abstract

We investigate the chemo-dynamical effects of multiple supernova explosions in the central region of primordial galaxies using three-dimensional hydrodynamical simulations of the inhomogenous interstellar medium down to parsec-scales. We find that the final protogalactic structure and metal distribution depend strongly on the number of SNe. Specifically, 1) 1000 SNe after an instantaneous burst of star formation are sufficient to almost completely blow away the gas in these systems, whereas 2) 100 SN explosions trigger the collapse of the protogalactic cloud, leading to the formation of a cold, dense clumpy disk (n > 300 cm^-3) with metallicity, Z = 4 10^-4 Z_sun. These results imply that the metallicity of the ``second generation'' of stars could be Z ~ 10^-4 Z_sun, and that the environment to form metal-free stars in protogalaxies may be lost relatively quickly (< 10^7 yr) after the first burst of Z=0 star formation. The recently discovered ultra-metal-poor star (Christlieb et al. 2002) may represent surviving members of such second-generation star formation.