  We carry out a numerical study of the effects of supernova-driven shocks on
galaxy formation at z=9. These "cosmic explosions" can have a significant
impact on galaxies forming nearby. We study such interactions in two key cases.
In the first case in which the forming galaxy has already virialized, the
impinging shock has only a small effect (< 1% of the gas is removed) and star
formation continues relatively unimpeded. However, in the second case in which
the nearby forming galaxy is at the more diffuse turn-around stage, a large
fraction (~70%) of the gas is stripped away from the host dark-matter halo and
ejected into the intergalactic medium. As the time spent near turn-around is
much longer than the interval from virialization to galaxy formation due to
strong radiative losses, we expect the second case to be more representative of
the majority of outflow-galaxy interactions. Thus SN-driven pregalactic
outflows may be an efficient mechanism for inhibiting the formation of
neighbouring galaxies at high redshift. We briefly outline the possible
cosmological consequences of this effect.
