Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations
Abstract
Within lambda cold dark matter (ΛCDM), dwarf galaxies like the Large Magellanic Cloud (LMC) are expected to host numerous dark matter subhaloes, several of which should host faint dwarf companions. Recent Gaia proper motions confirm new members of the LMC system in addition to the previously known SMC, including two classical dwarf galaxies (M_∗ > 10⁵ M⊙; Carina and Fornax) as well as several ultrafaint dwarfs (Car2, Car3, Hor1, and Hyd1). We use the Feedback In Realistic Environments (FIRE) simulations to study the dark and luminous (down to ultrafaint masses, M_∗ ∼ 6 × 10³ M_⊙) substructure population of isolated LMC-mass hosts (M₂₀₀ₘ = 1–3 × 10¹¹ M_⊙) and place the Gaia + DES results in a cosmological context. By comparing number counts of subhaloes in simulations with and without baryons, we find that, within 0.2 r₂₀₀ₘ, LMC-mass hosts deplete ∼30 per cent of their substructure, significantly lower than the ∼70 per cent of substructure depleted by Milky Way (MW) mass hosts. For our highest resolution runs (m_(bary) = 880 M_⊙), ∼5−10 subhaloes form galaxies with M_∗ ≥ 10⁴ M_⊙ , in agreement with the seven observationally inferred pre-infall LMC companions. However, we find steeper simulated luminosity functions than observed, hinting at observation incompleteness at the faint end. The predicted DM content for classical satellites in FIRE agrees with observed estimates for Carina and Fornax, supporting the case for an LMC association. We predict that tidal stripping within the LMC potential lowers the inner dark matter density of ultrafaint companions of the LMC. Thus, in addition to their orbital consistency, the low densities of dwarfs Car2, Hyd1, and Hyd2 reinforce their likelihood of Magellanic association.
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). The authors would like to thank Phil Hopkins for facilitating access to the FIRE runs and stimulating discussions of the simulations and science herein. We also thank Coral Wheeler, Shea Garrison-Kimmel, and the rest of the FIRE Local Universe collaboration for their thought-provoking insight and advice. We are grateful to the anonymous referee for a constructive report that helped improve this manuscript, as well as to Marius Cautun and Marcel Pawlowski for their helpful suggestions. LVS acknowledges support from NASA through the HST Programs AR-14582, AR-14583 and from the Hellman Foundation. AW was supported by NASA, through ATP grant 80NSSC18K1097 and HST grants GO-14734 and AR-15057 from STScI. MBK acknowledges support from NSF grant AST-1517226 and CAREER grant AST-1752913 and from NASA grants NNX17AG29G and HST-AR-14282, HST-AR-14554, HST-AR-15006, and HST-GO-14191 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. TKC was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. We ran simulations using XSEDE supported by NSF grant ACI-1548562, Blue Waters via allocation PRAC NSF.1713353 supported by the NSF, and NASA HEC Program through the NAS Division at Ames Research Center.Additional details
- Eprint ID
- 118696
- Resolver ID
- CaltechAUTHORS:20230105-893612000.13
- HST-AR-14282
- NASA
- HST-AR-14583
- NASA
- Hellman Fellowship
- 80NSSC18K1097
- NASA
- HST-GO-14734
- NASA
- HST-AR-15057
- NASA
- AST-1517226
- NSF
- AST-1752913
- NSF
- NNX17AG29G
- NASA
- HST-AR-14282
- NASA
- HST-AR-14554
- NASA
- HST-AR-15006
- NASA
- HST-GO-14191
- NASA
- NAS5-26555
- NASA
- AST-1715101
- NSF
- Cottrell Scholar of Research Corporation
- ACI-1548562
- NSF
- OAC-1713353
- NSF
- Created
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2023-01-20Created from EPrint's datestamp field
- Updated
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2023-01-20Created from EPrint's last_modified field