Uncertainties in supernova input rates drive qualitative differences in simulations of galaxy evolution

Feedback from core collapse supernovae (SNe), the final stage of evolution massive stars, is a key element in galaxy formation theory. The energy budget SN feedback, as well duration over which SNe occur, are constrained by stellar lifetime models and minimum mass star that ends its life SN. Simplifying approximations for this rate ubiquitous simulation studies. We show here how choice timings ($t_0$ delay between first SN, $\tau_{\rm SN}$ injection, progenitor mass) drive changes regulation outflow launching. Extremely long delays instantaneous injection $(t_0 << 20\;\rm{Myr})$ reduces stronger outflows compared smaller delays. This effect primarily driven enhanced clustering young stars. With continuous energy, longer durations results larger fraction deposited low ambient gas densities, where cooling losses lower. particularly when mass, also sets total budget. These underlying uncertainties mean despite advances sub-grid modeling serious difficulties constraining strength feedback remain. recommend future simulations use realistic durations, bound their using budgets progenitors $7M_\odot$ $9M_\odot$.