(Star)bursts of FIRE: Observational signatures of bursty star formation in galaxies

Martin Sparre*, Christopher C. Hayward, Robert Feldmann, Claude André Faucher-Giguère, Alexander L. Muratov, Dušan Kereš, Philip F. Hopkins

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

161 Scopus citations


Galaxy formation models are now able to reproduce observed relations such as the relation between galaxies' star formation rates (SFRs) and stellar masses (M*) and the stellar-mass- halo-mass relation. We demonstrate that comparisons of the short-time-scale variability in galaxy SFRs with observational data provide an additional useful constraint on the physics of galaxy formation feedback. We apply SFR indicators with different sensitivity time-scales to galaxies from the Feedback in Realistic Environments (FIRE) simulations. We find that the SFR-M* relation has a significantly greater scatter when the Hα-derived SFR is considered compared with when the far-ultraviolet (FUV)-based SFR is used. This difference is a direct consequence of bursty star formation because the FIRE galaxies exhibit order-of-magnitude SFR variations over time-scales of a few Myr. We show that the difference in the scatter between the simulated Hα- and FUV-derived SFR-M* relations at z = 2 is consistent with observational constraints. We also find that the Hα/FUV ratios predicted by the simulations at z = 0 are similar to those observed for local galaxies except for a population of low-mass (M* ≲109.5M) simulated galaxies with lower Hα/FUV ratios than observed. We suggest that future cosmological simulations should compare the Hα/FUV ratios of their galaxies with observations to constrain the feedback models employed.

Original languageEnglish (US)
Pages (from-to)88-104
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Apr 1 2017


  • Cosmology: theory
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: star formation
  • Galaxies: starburst
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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