Explosions in the early universe

Abstract

We have constructed a series of simulations of spherically symmetric explosions in an otherwise unperturbed cosmology. The numerical hydrodynamics code includes effects due to electron conductivity, radiative cooling gravity, ion viscosity, and the difference between the electron and ion temperatures. The initial redshift of the explosions has been varied between a redshift of 50 and a redshift of 2. The initial energies of the explosions range from 10/sup 59/ ergs to 10/sup 61/ ergs, appropriate to the energy input from quasars or primeval galaxies. We discuss the evolution of these explosions in terms of the quantities most clearly related to observable effects on the intergalactic medium, including their size, total thermal and kinetic energies, shell temperatures and densities, and mean interior pressure as a function of epoch. In all cases most of the matter passed by the shock is eventually swept up into relatively dense shells. For certain epochs and ranges of energy, nonradial instabilities can occur, of either the Rayleigh-Taylor or the Jeans type, leading to the formation of dense fragments. The former instability is more relevant to low-energy events and may produce the Ly..cap alpha.. clouds seen in absorption with large-energy events producing massive shells subject to gravitationalmore » instabilities and possibly the production of bound stellar systems. Most of the simulations were run with the present total matter density equal to 10% of the critical density. For this case final (current) and radii and peculiar velocities of 10/sup 61/-erg explosions are 4.26 Mpc and 19.2 km s/sup -1/, for an initial redshift of 10, and 3.64 Mpc and 10.2 km s/sup -1/, for an initial redshift of 20.« less