The Local Group on FIRE: Dwarf galaxy populations across a suite of hydrodynamic simulations

Creators: Garrison-Kimmel, Shea; Hopkins, Philip F.; Wetzel, Andrew; Bullock, James S.; Boylan-Kolchin, Michael; Kereš, Dušan; Faucher-Giguère, Claude-André; El-Badry, Kareem; Lamberts, Astrid; Quataert, Eliot; Sanderson, Robyn

Abstract

We present a new set of high-resolution hydrodynamic cosmological zoom-in simulations that apply the Feedback In Realistic Environments physics to both Local Group (LG)-like and isolated Milky Way (MW)-like volumes (10 host systems in total with a baryonic particle mass ≃3500−7000M⁠). We study the stellar mass functions, circular velocity or mass profiles, and velocity dispersions of the dwarf galaxy populations. The simulations reproduce the stellar mass function and central densities of MW satellite dwarfs for M∗≥10^(5.5) M⊙ and predict the existence of ∼3 unidentified galaxies with M∗∼10^5M⊙ within 300 kpc of the MW. Overall, we find no evidence for the classical missing satellites or too-big-to-fail (TBTF) problems for satellite galaxies in our sample. Among the satellites, TBTF is resolved primarily by subhalo disruption and overall mass-loss; central density profiles of subhaloes are of secondary importance. For non-satellite galaxies, our LG-like simulations predict as many as ∼10 as-of-yet unseen galaxies at distances 0.3−1Mpc from both hosts, with M∗≃10^(5−6) M⊙ (in haloes with V_(max) ∼ 20 km s^(−1)), albeit with large halo-to-halo variance. None of our simulations produces a compact, baryon-dominated, high-density dwarf elliptical-type galaxy (with V_(circ) ≳ 35 km s^(−1) at r < 1kpc), of which six may appear in the LG (but none in the MW). It may therefore remain a challenge to reproduce the full diversity of the dwarf population, including both the highest and lowest density systems.

Additional Information

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 May 9. Received 2019 March 29; in original form 2018 June 8. Published: 16 May 2019. The authors thank Evan Kirby, Coral Wheeler, Lina Necib, Alejandro Benitez-Llambay, and Cameron Hummels for valuable discussions, and Alexander Knebe and Oliver Hahn for making AHF and MUSIC, respectively, publicly available. Support for SGK was provided 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. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NSF Collaborative Research Grant #1715847 and CAREER grant #1455342. AW was supported by a Caltech-Carnegie Fellowship, in part through the Moore Center for Theoretical Cosmology and Physics at Caltech, and by NASA through grants HST-GO-14734 and HST-AR-15057 from STScI. JSB was supported by NSF grant AST-1518291 and by NASA through HST theory grants (programs AR-13921, AR-13888, and AR-14282.001) awarded by STScI, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. 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 STScI. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. CAFG was supported by NSF through grants AST-1412836, AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant NNX15AB22G, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. KEB was supported by a Berkeley graduate fellowship, a Hellman award for graduate study, and a NSF Graduate Research Fellowship. EQ was supported in part by NSF grant AST-1715070 and a Simons Investigator Award from the Simons Foundation. RS is supported by a NSF Astronomy & Astrophysics Postdoctoral Fellowship under grant AST-1400989. Numerical calculations were run on the Caltech compute cluster 'Wheeler', allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, NASA HEC SMD-16-7223 and SMD-16-7592, and High Performance Computing at Los Alamos National Labs. This work also made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013), matplotlib (Hunter 2007), numpy (van der Walt, Colbert & Varoquaux 2011), scipy (Jones et al. 2001), ipython (Perez & Granger 2007), yt (Turk et al. 2011), and NASA's Astrophysics Data System. This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958.

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