Discrete effects in stellar feedback: Individual Supernovae, Hypernovae, and IMF Sampling in Dwarf Galaxies

Kung Yi Su*, Philip F. Hopkins, Christopher C. Hayward, Xiangcheng Ma, Michael Boylan-Kolchin, Daniel Kasen, Dušan Kereš, Claude André Faucher-Giguère, Matthew E. Orr, Coral Wheeler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Using high-resolution simulations from the FIRE-2 (Feedback In Realistic Environments) project, we study the effects of discreteness in stellar feedback processes on the evolution of galaxies and the properties of the interstellar medium (ISM). We specifically consider the discretization of supernovae (SNe), including hypernovae (HNe), and sampling the initial mass function (IMF). We study these processes in cosmological simulations of dwarf galaxies with z = 0 stellar masses M∗ ∼ 104-3 × 106,M (halo masses ∼ 109-1010, M). We show that the discrete nature of individual SNe (as opposed to a model in which their energy/momentum deposition is continuous overtime, similar to stellar winds) is crucial in generating a reasonable ISM structure and galactic winds and in regulating dwarf stellar masses. However, once SNe are discretized, accounting for the effects of IMF sampling on continuous mechanisms such as radiative feedback and stellar mass-loss (as opposed to adopting IMF-averaged rates) has weak effects on galaxy-scale properties. We also consider the effects of rare HNe events with energies ∼ 1053, erg. The effects of HNe are similar to the effects of clustered explosions of SNe-which are already captured in our default simulation setup-and do not quench star formation (provided that the HNe do not dominate the total SNe energy budget), which suggests that HNe yield products should be observable in ultra-faint dwarfs today.

Original languageEnglish (US)
Pages (from-to)1666-1675
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Oct 1 2018


  • ISM: jets and outflows
  • ISM: structure
  • cosmology: theory
  • galaxies: star formation
  • methods: numerical
  • supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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