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Hot-mode accretion and the physics of thin-disk galaxy formation

Hafen, Zachary and Stern, Jonathan and Bullock, James and Gurvich, Alex B. and Yu, Sijie and Faucher-Giguère, Claude-André and Fielding, Drummond B. and Anglés-Alcázar, Daniel and Quataert, Eliot and Wetzel, Andrew and Starkenburg, Tjitske and Boylan-Kolchin, Michael and Moreno, Jorge and Feldmann, Robert and El-Badry, Kareem and Chan, T. K. and Trapp, Cameron and Kereš, Dušan and Hopkins, Philip F. (2022) Hot-mode accretion and the physics of thin-disk galaxy formation. . (Unpublished)

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We use FIRE simulations to study disk formation in z ~ 0, Milky Way-mass galaxies, and conclude that a key ingredient for the formation of thin stellar disks is the ability for accreting gas to develop an aligned angular momentum distribution via internal cancellation *prior* to joining the galaxy. Among galaxies with a high fraction of their young stars (>70%) in a thin disk (h/R~0.1) we find that: (i) hot, virial-temperature gas dominates the inflowing gas mass on halo scales (>~20 kpc), with radiative losses offset by compression heating; (ii) this hot accretion proceeds until angular momentum support slows inward motion, at which point the gas cools to T~10⁴ K or less; (iii) prior to cooling, the accreting gas develops an angular momentum distribution that is aligned with the galaxy disk, and while cooling transitions from a quasi-spherical spatial configuration to a more flattened, disk-like configuration. We show that the existence of this "rotating cooling flow" accretion mode is strongly correlated with the fraction of stars forming in a thin disk among a sample of 17 z~0 galaxies spanning a halo mass range of 10^(10.5) solar masses to 10¹² solar masses, or a stellar mass range 10⁸ solar masses to 10¹¹ solar masses. Notably, galaxies with a thick disk or irregular morphology do not undergo significant angular momentum alignment of gas prior to accretion and show no correspondence between halo gas cooling and flattening. Our results suggest that rotating cooling flows (or, more generally, rotating subsonic flows) that become coherent and angular momentum-supported prior to direct deposition onto the galaxy are likely a necessary condition for the formation of thin, star-forming disk galaxies in a LambdaCDM universe.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper ItemFIRE ItemGIZMO code ItemAccompanying interactive visualization
Hafen, Zachary0000-0001-7326-1736
Stern, Jonathan0000-0002-7541-9565
Bullock, James0000-0003-4298-5082
Yu, Sijie0000-0002-1019-0341
Faucher-Giguère, Claude-André0000-0002-4900-6628
Fielding, Drummond B.0000-0003-3806-8548
Anglés-Alcázar, Daniel0000-0001-5769-4945
Quataert, Eliot0000-0001-9185-5044
Wetzel, Andrew0000-0003-0603-8942
Boylan-Kolchin, Michael0000-0002-9604-343X
Moreno, Jorge0000-0002-3430-3232
Feldmann, Robert0000-0002-1109-1919
El-Badry, Kareem0000-0002-6871-1752
Chan, T. K.0000-0003-2544-054X
Trapp, Cameron0000-0001-7813-0268
Kereš, Dušan0000-0002-1666-7067
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:Attribution 4.0 International (CC BY 4.0). ZH was supported by a Gary A. McCue postdoctoral fellowship at UC Irvine. JS was supported by the Israel Science Foundation (grant No. 2584/21) and by the German Science Foundation via DIP grant STE 1869/2-1 GE 625/17-1. JSB was supported by NSF grant AST-1910346. ABG was supported by an NSF-GRFP under grant DGE-1842165 and was additionally supported by NSF grants DGE-0948017 and DGE-145000. SY was supported by NSF grant AST-1910346. CAFG was supported by NSF through grants AST1715216, AST-2108230, and CAREER award AST-1652522; by NASA through grant 17-ATP17-0067; by STScI through grant HST-AR-16124.001-A; and by the Research Corporation for Science Advancement through a Cottrell Scholar Award. DBF is supported by the Simons Foundation through the Flatiron Institute. DAA was supported in part by NSF grants AST-2009687 and AST-2108944 and by the Flatiron Institute, which is supported by the Simons Foundation. EQ was supported in part by a Simons Investigator grant from the Simons Foundation and NSF grant 2107872. AW received support from: NSF grants CAREER 2045928 and 2107772; NASA ATP grant 80NSSC20K0513; HST grants AR-15809 and GO-15902 from STScI; a Scialog Award from the Heising-Simons Foundation; and a Hellman Fellowship. MBK acknowledges support from NSF CAREER award AST-1752913, NSF grants AST-1910346 and AST2108962, NASA grant NNX17AG29G, and HST-AR-15006, HST-AR-15809, HST-GO-15658, HST-GO-15901, HST-GO-15902, HST-AR-16159, and HST-GO-16226 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. JM gratefully acknowledges sabbatical leave support from Pomona College and the Harry and Grace Steele Foundation. RF acknowledges financial support from the Swiss National Science Foundation (grant no PP00P2_194814 and 200021_188552). TKC is supported by Science and Technology Facilities Council (STFC) astronomy consolidated grant ST/P000541/1 and ST/T000244/1. CT and DK were supported by NSF grants AST-1715101 and AST-2108314. Numerical calculations were performed on the Quest computing cluster at Northwestern University, the Wheeler computing cluster at Caltech, XSEDE allocations TG-AST130039, TG-AST120025, TG-AST140064, and TG-AST140023, Blue Waters PRAC allocation NSF.1713353, NASA HEC allocation SMD16-7592, and allocations AST21010 and AST20016 supported by the NSF and TACC. This research benefited from the Halo21 KITP workshop which was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. This research used the Python programming language and the following modules: Firefly (Geller & Gurvich 2018), Numpy (Harris et al. 2020), Matplotlib (Hunter 2007), pytest (Krekel et al. 2004), Jug (Coelho 2017), h5py (Collette 2013), SciPy (Virtanen et al. 2020), pandas (McKinney 2010; Reback et al. 2020), palettable (, and Numba (Lam et al. 2015). DATA AVAILABILITY. The data underlying this article will be shared on reasonable request to the corresponding author (ZH). The simulation initial conditions, snapshot files, and visualization can be found in A public version of the GIZMO simulation code is available phopkins/Site/GIZMO.html.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
University of California, IrvineUNSPECIFIED
Israel Science Foundation2584/21
Deutsche Forschungsgemeinschaft (DFG)STE 1869/2-1 GE 625/17-1
NSF Graduate Research FellowshipDGE-1842165
NSF Graduate Research FellowshipDGE-0948017
NSF Graduate Research FellowshipDGE-145000
Cottrell Scholar of Research CorporationUNSPECIFIED
Simons FoundationUNSPECIFIED
Flatiron InstituteUNSPECIFIED
NASA Hubble FellowshipAR-15809
NASA Hubble FellowshipGO-15902
Heising-Simons FoundationScialog Award
Hellman FellowshipUNSPECIFIED
Harry and Grace Steele FoundationUNSPECIFIED
Swiss National Science Foundation (SNSF)PP00P2_194814
Swiss National Science Foundation (SNSF)200021_188552
Science and Technology Facilities Council (STFC)ST/P000541/1
Science and Technology Facilities Council (STFC)ST/T000244/1
Subject Keywords:galaxies: disk – galaxies: evolution – galaxies: haloes – cosmology: theory
Record Number:CaltechAUTHORS:20220228-183316128
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113652
Deposited By: George Porter
Deposited On:28 Feb 2022 23:53
Last Modified:28 Feb 2022 23:54

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