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 ( \lower 2.15 pt \hbox { $ \buildrel < \over { \sim } $ } 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 ( \approx 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 .