Supernova Explosions in the Early Universe: Evolution of Radiative Remnants and the Halo Destruction Efficiency

We study the evolution of supernova (SN) remnants of the first stars, taking proper account of the radiative feedback of the progenitor stars on the surroundings. We carry out a series of one-dimensional hydrodynamic simulations with radiative cooling, starting from initial configurations that are drawn from the results of our earlier radiation hydrodynamic simulations of the first H II regions. We primarily consider explosion energies E_SN=10⁵¹-10⁵³ ergs, appropriate for various types of single Population III supernovae, and also explore cases with greater energy to model multiple explosions. In low-mass (<~10⁶ M_solar) halos, the stellar radiation significantly reduces the ambient gas density prior to the SN explosion. The blast wave quickly propagates over the halo's virial radius, leading to complete evacuation of the gas even with an input energy of 10⁵⁰ ergs. We find that a large fraction of the remnant's thermal energy is lost in 10⁵-10⁷ yr by line cooling, whereas for larger explosion energies, the remnant expands even more rapidly with decreasing interior density and cools predominantly via the inverse Compton process, adding the bulk of the energy to cosmic microwave background photons. In higher mass (~10⁷ M_solar) halos, the gas density near the explosion site remains high (>~10⁴ cm^-3), and the SN shock is heavily confined; the thermal energy of the remnant is quickly radiated away by free-free emission, even if the total input energy exceeds the binding energy of halos by 2 orders of magnitude. We show that the efficiency of halo destruction is determined not only by the explosion energy but also by the gas density profile and thus is controlled by radiative feedback prior to the explosion. We compute the emissivity of the remnants in various energy ranges and examine their detectability by future observations. Several implications of our results for the formation of the first quasars and second-generation stars in the universe are also discussed.