We explore when supernovae can ( and can not ) regulate the star formation and bulge growth in galaxies based on a sample of 18 simulated galaxies .
The simulations include key physics such as evaporation and conduction , neglected in prior work , and required to correctly model superbubbles resulting from stellar feedback .
We show that for galaxies with virial masses > 10 ^ { 12 } \ > { M _ { \odot } } , supernovae alone can not prevent excessive star formation .
This failure occurs due to a shutdown of galactic winds , with wind mass loadings falling from \eta \sim 10 to \eta < 1 .
In more massive systems , this transfer of baryons to the circumgalactic medium falters earlier on and the galaxies diverge significantly from observed galaxy scaling relations and morphologies .
The decreasing efficiency is simply due to a deepening potential well preventing gas escape .
This implies that non-supernova feedback mechanisms must become dominant for galaxies with stellar masses greater than \sim 4 \times 10 ^ { 10 } \ > { M _ { \odot } } .
The runaway growth of the central stellar bulge , strongly linked to black hole growth , suggests that feedback from active galactic nuclei is the probable mechanism .
Below this mass , supernovae alone are able to produce a realistic stellar mass fraction , star formation history and disc morphology .