Some Stars Fade Quietly: Varied Supernova Explosion Outcomes and Their Effects on the Multiphase Interstellar Medium

Abstract

We present results from galaxy evolution simulations with a multiphase interstellar medium (ISM), a mass resolution of 4 M _⊙ , and a spatial resolution of 0.5 pc. These simulations include a resolved stellar stellar feedback model. Our fiducial run WLM-fid adopts 10 ^51 erg for the supernova (SN) energy. Among the remaining seven simulations, there are two runs where we vary this number by fixing the energy at 10 ^50 erg and 10 ^52 erg (WLM-1e50 and WLM-1e52). Additionally, we carry out one run with variable SN-energy (WLM-variable) and run two simulations where only 10% or 60% of stars explode as SNe with 10 ^51 erg, while the remaining stars do not explode (WLM-60prob and WLM-10prob). We find that the variation in the SN energy, has only minor effects: the star formation rate changes by roughly a factor of 2 compared to WLM-fid, and the strength of the galactic outflows in mass and energy is reduced by 30%, with typical values of η _m ∼ 0.1 and η _e ∼ 0.05 (at a height of 3 kpc after the hot wind is fully decoupled from the galactic ISM). In contrast, the increase and decrease in the canonical SN-energy have a clear impact on the phase structure, with loading factors that are at least 10 times lower/higher and a clear change in the phase structure (the energy loading is normalized self-consistently to the initial mass function averaged explosion energy). We conclude that these modulations are driven not by the minor change in SN-energy but rather by the likelihood of whether or not an event occurs when variable SN energies are applied.

Keywords

• Galactic winds
• Galaxy evolution
• Hydrodynamical simulations
• Stellar feedback
• Interstellar medium