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Be it therefore resolved: Cosmological Simulations of Dwarf Galaxies with Extreme Resolution

Wheeler, Coral and Hopkins, Philip F. and Pace, Andrew B. and Garrison-Kimmel, Shea and Boylan-Kolchin, Michael and Wetzel, Andrew and Bullock, James S. and Kereš, Dušan and Faucher-Giguère, Claude-André and Quataert, Eliot (2018) Be it therefore resolved: Cosmological Simulations of Dwarf Galaxies with Extreme Resolution. . (Unpublished)

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We study a suite of extremely high-resolution cosmological FIRE simulations of dwarf galaxies (M_(halo) ≲ 10^(10) 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 M_(halo) ≳ 10^(8.6) M_⊙ is populated by a resolved {\em stellar} galaxy, suggesting very low-mass dwarfs may be ubiquitous in the field. Our ultra-faint dwarfs (UFDs; M∗ < 10^5 M_⊙) have their star formation truncated early (z ≳ 2), likely by reionization, while classical dwarfs (M∗ > 10^5 M_⊙) continue forming stars to z < 0.5. The systems have bursty star formation (SF) histories, forming most of their stars in periods of elevated SF strongly clustered in both space and time. This allows our dwarf with M∗/M_(halo) > 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∗ > 10^4 M_⊙ have half-mass radii (R_(1/2)) in agreement with Local Group (LG) dwarfs; dynamical mass vs. R_(1/2) and the degree of rotational support 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).

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Hopkins, Philip F.0000-0003-3729-1684
Garrison-Kimmel, Shea0000-0002-4655-8128
Boylan-Kolchin, Michael0000-0002-9604-343X
Wetzel, Andrew0000-0003-0603-8942
Kereš, Dušan0000-0002-1666-7067
Faucher-Giguère, Claude-André0000-0002-4900-6628
Quataert, Eliot0000-0001-9185-5044
Additional Information:CW is supported by the Lee A. DuBridge Postdoctoral Scholarship in Astrophysics. Support for PFH and SGK was provided by an Alfred P. Sloan Research Fellowship, NSF Collaborative Research Grant #1715847 and CAREER grant #1455342, and NASA grants NNX15AT06G, JPL 1589742, 17-ATP17-0214. ABP acknowledges generous support from the George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy at Texas A&M University. SGK acknowledges additional support by NASA through Einstein Postdoctoral Fellowship grant number PF5-160136 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. MBK acknowledges support from NSF grant AST-1517226 and CAREER grant AST-1752913 and from NASA grants NNX17AG29G and HST-AR-13888, HST-AR-13896, HST-AR-14282, HST-AR-14554, HST-AR-15006, HST-GO-12914, and HST-GO-14191 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grants NNX15AB22G and 17-ATP17-0067, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. Numerical calculations were run on the Caltech compute cluster “Wheeler,” allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592.
Funding AgencyGrant Number
Lee A. DuBridge FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
George P. and Cynthia Woods Institute for Fundamental Physics and AstronomyUNSPECIFIED
NASA Einstein FellowshipPF5-160136
Cottrell Scholar of Research CorporationUNSPECIFIED
Subject Keywords:galaxies: dwarf – galaxies: formation – galaxies: star formation – galaxies: kinematics and dynamics – Local Group
Record Number:CaltechAUTHORS:20190206-105648233
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92732
Deposited By: George Porter
Deposited On:07 Feb 2019 15:50
Last Modified:07 Feb 2019 15:50

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