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~10⁶ M_solar) at redshifts z~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=10⁵¹ and 10⁵³ ergs. Whereas the lower explosion energy leaves part of the halo intact, we find that the more energetic explosion leads to the complete disruption of the gas in the minihalo and expels >~90% of the stellar metals into a region ~1 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>~10^-4 Z_solar, already at z>~15.