The origin of the diverse morphologies and kinematics of Milky Way-mass galaxies in the FIRE-2 simulations
Abstract
We use hydrodynamic cosmological zoom-in simulations from the Feedback in Realistic Environments project to explore the morphologies and kinematics of 15 Milky Way (MW)-mass galaxies. Our sample ranges from compact, bulge-dominated systems with 90 per cent of their stellar mass within 2.5 kpc to well-ordered discs that reach ≳15 kpc. The gas in our galaxies always forms a thin, rotation-supported disc at z = 0, with sizes primarily determined by the gas mass. For stars, we quantify kinematics and morphology both via the fraction of stars on disc-like orbits and with the radial extent of the stellar disc. In this mass range, stellar morphology and kinematics are poorly correlated with the properties of the halo available from dark matter-only simulations (halo merger history, spin, or formation time). They more strongly correlate with the gaseous histories of the galaxies: those that maintain a high gas mass in the disc after z ∼ 1 develop well-ordered stellar discs. The best predictor of morphology we identify is the spin of the gas in the halo at the time the galaxy formed 1/2 of its stars (i.e. the gas that builds the galaxy). High-z mergers, before a hot halo emerges, produce some of the most massive bulges in the sample (from compact discs in gas-rich mergers), while later-forming bulges typically originate from internal processes, as satellites are stripped of gas before the galaxies merge. Moreover, most stars in z = 0 MW-mass galaxies (even z = 0 bulge stars) form in a disc: ≳60--90 per cent of stars begin their lives rotationally supported.
Additional Information
© 2018 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 2018 September 10. Received 2018 August 13; in original form 2017 December 11. The authors thank Astrid Lamberts, Coral Wheeler, Evan Kirby, Laura Sales, and Virginia Kilborn for valuable discussions, and the anonymous referee for their helpful comments. We also thank the Santa Cruz Galaxy Formation Workshop, the Galaxy Formation and Evolution in Southern California (GalFRESCA) workshop, and the Swinburne-Caltech workshop for spawning useful discussions that significantly improved the quality of the manuscript, and we thank Alexander Knebe, Peter Behroozi, and Oliver Hahn, respectively, for making AHF, rockstar and consistent-trees, and MUSIC 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 no. 1715847 and CAREER grant no. 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. RES is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under grant AST-1400989. KEB was supported by a Berkeley graduate fellowship, a Hellman award for graduate study, and an NSF Graduate Research Fellowship. EQ was supported in part by NSF grant AST-1715070 and a Simons Investigator Award from the Simons Foundation. JSB was supported by NSF grant AST-1518291 and by NASA through Hubble Space Telescope 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. ZH and CAFG were supported by NSF through grants AST-1412836, AST-1517491, AST-1715216, and CAREER award AST-1652522, and by NASA through grant NNX15AB22G, and ZH additionally acknowledges support from support from Northwestern University through the 'Reach for the Stars' program. FvdV acknowledges support from the Klaus Tschira Foundation. The Flatiron Institute is supported by the Simons Foundation. DK acknowledges support from NSF grant AST-1412153, NSF grant AST-1715101, and the Cottrell Scholar Award from the Research Corporation for Science Advancement. MBK acknowledges support from NSF grant AST-1517226 and from NASA grants NNX17AG29G and HST-AR-13896, HST-AR-14282, HST-AR-14554, HST-GO-12914, and HST-GO-14191 from STScI. 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 et al. 2013), MATPLOTLIB (Hunter 2007), NUMPY (van der Walt, Colbert & Varoquaux 2011), SCIPY (Jones et al. 2001), IPYTHON (Perez & Granger 2007), and NASA's Astrophysics Data System.Attached Files
Published - sty2513.pdf
Accepted Version - nihms-997000.pdf
Submitted - 1712.03966.pdf
Files
Additional details
- PMCID
- PMC6310044
- Eprint ID
- 91511
- Resolver ID
- CaltechAUTHORS:20181205-145100415
- PF5-160136
- NASA Einstein Fellowship
- NAS8-03060
- NASA
- Alfred P. Sloan Foundation
- AST-1715847
- NSF
- AST-1455342
- NSF
- Caltech-Carnegie Fellowship
- Caltech Moore Center for Theoretical Cosmology and Physics
- HST-GO-14734
- NASA
- HST-AR-15057
- NASA
- AST-1400989
- NSF Astronomy and Astrophysics Fellowship
- University of California, Berkeley
- Hellman Fellowship
- NSF Graduate Research Fellowship
- AST-1715070
- NSF
- Simons Foundation
- AST-1518291
- NSF
- AR-13921
- NASA Hubble Fellowship
- AR-13888
- NASA Hubble Fellowship
- AR-14282.001
- NASA Hubble Fellowship
- NAS5-26555
- NASA
- AST-1412836
- NSF
- AST-1517491
- NSF
- AST-1715216
- NSF
- AST-1652522
- NSF
- NNX15AB22G
- NASA
- Northwestern University
- Klaus Tschira Foundation
- AST-1412153
- NSF
- AST-1715101
- NSF
- Cottrell Scholar of Research Corporation
- AST-1517226
- NSF
- NNX17AG29G
- NASA
- HST-AR-13896
- NASA
- HST-AR-14282
- NASA
- HST-AR-14554
- NASA
- HST-GO-12914
- NASA
- HST-GO-14191
- NASA
- TG-AST130039
- NSF
- OAC-1713353
- NSF
- SMD-16-7223
- NASA
- SMD-16-7592
- NASA
- Created
-
2018-12-05Created from EPrint's datestamp field
- Updated
-
2023-01-05Created from EPrint's last_modified field
- Caltech groups
- TAPIR, Moore Center for Theoretical Cosmology and Physics, Astronomy Department