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The In Situ Origins of Dwarf Stellar Outskirts in FIRE-2

Kado-Fong, Erin; Sanderson, Robyn E.; Greene, Jenny E.; Cunningham, Emily C.; Wheeler, Coral; Chan, T.K.; El-Badry, Kareem; Hopkins, Philip F.; Wetzel, Andrew; Boylan-Kolchin, Michael; Faucher-Giguère, Claude-André; Huang, Song; Quataert, Eliot; Starkenburg, Tjitske

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Authors

Erin Kado-Fong

Robyn E. Sanderson

Jenny E. Greene

Emily C. Cunningham

Coral Wheeler

Kareem El-Badry

Philip F. Hopkins

Andrew Wetzel

Michael Boylan-Kolchin

Claude-André Faucher-Giguère

Song Huang

Eliot Quataert

Tjitske Starkenburg



Abstract

Extended, old, and round stellar halos appear to be ubiquitous around high-mass dwarf galaxies (108.5 < M⋆/M⊙ < 109.6) in the observed universe. However, it is unlikely that these dwarfs have undergone a sufficient number of minor mergers to form stellar halos that are composed of predominantly accreted stars. Here, we demonstrate that FIRE-2 (Feedback in Realistic Environments) cosmological zoom-in simulations are capable of producing dwarf galaxies with realistic structures, including both a thick disk and round stellar halo. Crucially, these stellar halos are formed in situ, largely via the outward migration of disk stars. However, there also exists a large population of “nondisky” dwarfs in FIRE-2 that lack a well-defined disk/halo and do not resemble the observed dwarf population. These nondisky dwarfs tend to be either more gas-poor or to have burstier recent star formation histories than the disky dwarfs, suggesting that star formation feedback may be preventing disk formation. Both classes of dwarfs underscore the power of a galaxy’s intrinsic shape—which is a direct quantification of the distribution of the galaxy’s stellar content—to interrogate the feedback implementation in simulated galaxies.

Citation

Kado-Fong, E., Sanderson, R. E., Greene, J. E., Cunningham, E. C., Wheeler, C., Chan, T., …Starkenburg, T. (2022). The In Situ Origins of Dwarf Stellar Outskirts in FIRE-2. Astrophysical Journal, 931(2), Article 152. https://doi.org/10.3847/1538-4357/ac6c88

Journal Article Type Article
Acceptance Date May 2, 2022
Online Publication Date Jun 6, 2022
Publication Date 2022-06
Deposit Date Jul 14, 2022
Publicly Available Date Jul 14, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 931
Issue 2
Article Number 152
DOI https://doi.org/10.3847/1538-4357/ac6c88

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.





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