Be it therefore resolved: Cosmological simulations of dwarf galaxies with 30 solar mass resolution

Coral Wheeler, Philip F. Hopkins, Andrew B. Pace, Shea Garrison-Kimmel, Michael Boylan-Kolchin, Andrew Wetzel, James S. Bullock, Dušan Kereš, Claude André Faucher-Giguère, Eliot Quataert

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


We study a suite of extremely high-resolution cosmological Feedback in Realistic Environments simulations of dwarf galaxies (Mhalo ≲ 1010 M☉), run to z = 0 with 30 M☉ resolution, sufficient (for the first time) to resolve the internal structure of individual supernovae remnants within the cooling radius. Every halo with Mhalo ≳ 108.6 M☉ is populated by a resolved stellar galaxy, suggesting very low-mass dwarfs may be ubiquitous in the field. Our ultra-faint dwarfs (UFDs; M < 105 M☉) have their star formation (SF) truncated early (z ≳ 2), likely by reionization, while classical dwarfs (M > 105 M☉) continue forming stars to z < 0.5. The systems have bursty star formation histories, forming most of their stars in periods of elevated SF strongly clustered in both space and time. This allows our dwarf with M/Mhalo > 10−4 to form a dark matter core >200 pc, while lower mass UFDs exhibit cusps down to ≲100 pc, as expected from energetic arguments. Our dwarfs with M > 104 M☉ have half-mass radii (R1/2) in agreement with Local Group (LG) dwarfs (dynamical mass versus R1/2 and stellar rotation also resemble observations). The lowest mass UFDs are below surface brightness limits of current surveys but are potentially visible in next-generation surveys (e.g. LSST). The stellar metallicities are lower than in LG dwarfs; this may reflect pre-enrichment of the LG by the massive hosts or Pop-III stars. Consistency with lower resolution studies implies that our simulations are numerically robust (for a given physical model).

Original languageEnglish (US)
Pages (from-to)4447-4463
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Dec 1 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies: dwarf
  • Galaxies: formation
  • Galaxies: kinematics and dynamics
  • Galaxies: star formation
  • Local Group


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