Star formation histories of dwarf galaxies in the FIRE simulations: Dependence on mass and Local Group environment

Shea Garrison-Kimmel*, Andrew Wetzel, Philip F. Hopkins, Robyn Sanderson, Kareem El-Badry, Andrew Graus, T. K. Chan, Robert Feldmann, Michael Boylan-Kolchin, Christopher C. Hayward, James S. Bullock, Alex Fitts, Jenna Samuel, Coral Wheeler, Dušan Kereš, Claude André Faucher-Giguère

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We study star formation histories (SFHs) of 500 dwarf galaxies (stellar mass M = 105–109 M) from FIRE-2 cosmological zoom-in simulations. We compare dwarfs around individual Milky Way (MW)-mass galaxies, dwarfs in Local Group (LG)-like environments, and true field (i.e. isolated) dwarf galaxies. We reproduce observed trends wherein higher mass dwarfs quench later (if at all), regardless of environment. We also identify differences between the environments, both in terms of ‘satellite versus central’ and ‘LG versus individual MW versus isolated dwarf central.’ Around the individual MW-mass hosts, we recover the result expected from environmental quenching: central galaxies in the ‘near field’ have more extended SFHs than their satellite counterparts, with the former more closely resemble isolated (true field) dwarfs (though near-field centrals are still somewhat earlier forming). However, this difference is muted in the LG-like environments, where both near-field centrals and satellites have similar SFHs, which resemble satellites of single MW-mass hosts. This distinction is strongest for M = 106–107 M but exists at other masses. Our results suggest that the paired halo nature of the LG may regulate star formation in dwarf galaxies even beyond the virial radii of the MW and Andromeda. Caution is needed when comparing zoom-in simulations targeting isolated dwarf galaxies against observed dwarf galaxies in the LG.

Original languageEnglish (US)
Pages (from-to)4574-4588
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Nov 11 2019


  • Cosmology: theory
  • Galaxies: dwarf
  • Galaxies: formation
  • Local Group

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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