  We present a Supernova (SN) feedback model that succeeds at describing the
chemical and energetic effects of SN explosions in galaxy formation
simulations. This new SN model has been coupled to GADGET-2 and works within a
new multiphase scheme which allows the description of a co-spatial mixture of
cold and hot interstellar medium phases.
  No ad hoc scale-dependent parameters are associated to these SN and
multiphase models making them particularly suited to studies of galaxy
formation in a cosmological framework. Our SN model succeeds not only in
setting a self-regulated star formation activity in galaxies but in triggering
collimated chemical-enriched galactic winds. The effects of winds vary with the
virial mass of the systems so that the smaller the galaxy, the larger the
fraction of swept away gas and the stronger the decrease in its star formation
activity. The fact that the fraction of ejected metals exceeds 60 per cent
regardless of mass, suggests that SN feedback can be the responsible mechanism
of the enrichment of the intergalactic medium to the observed levels.
