The first supernova explosions in the universe

We investigate the supernova explosions that end the lives of massive Population III stars in low-mass minihalos (M similar to 10(6) M-.) at redshifts z similar to 20. Employing the smoothed particle hydrodynamics method, we carry out numerical simulations in a cosmological setup of pair-instability supernovae with explosion energies of E-SN = 10(51) and 10(53) ergs. Whereas the lower explosion energy leaves part of the halo intact, we find that the more 51 10 energetic explosion leads to the complete disruption of the gas in the minihalo and expels greater than or similar to90% of the stellar metals into a region similar to1 kpc across over a timescale of 3-5 Myr. Because of this burstlike initial star formation episode, a large fraction of the universe could have been endowed with a metallicity floor, Z(min) greater than or similar to 10(-4) Z(.), already at z greater than or similar to 15.