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Gas kinematics, morphology and angular momentum in the FIRE simulations

El-Badry, Kareem and Quataert, Eliot and Wetzel, Andrew and Hopkins, Philip F. and Weisz, Daniel R. and Chan, T. K. and Fitts, Alex and Boylan-Kolchin, Michael and Kereš, Dušan and Faucher-Giguère, Claude-André and Garrison-Kimmel, Shea (2018) Gas kinematics, morphology and angular momentum in the FIRE simulations. Monthly Notices of the Royal Astronomical Society, 473 (2). pp. 1930-1955. ISSN 0035-8711.

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We study the z = 0 gas kinematics, morphology and angular momentum content of isolated galaxies in a suite of cosmological zoom-in simulations from the FIRE project spanning M_(star) = 10^(6–11) M_⊙. Gas becomes increasingly rotationally supported with increasing galaxy mass. In the lowest mass galaxies (M_(star) < 10^8 M_⊙), gas fails to form a morphological disc and is primarily dispersion and pressure supported. At intermediate masses (M_(star) = 10^(8–10) M_⊙), galaxies display a wide range of gas kinematics and morphologies, from thin, rotating discs to irregular spheroids with negligible net rotation. All the high-mass (M_(star) = 10^(10–11) M_⊙) galaxies form rotationally supported gas discs. Many of the haloes whose galaxies fail to form discs harbour high angular momentum gas in their circumgalactic medium. The ratio of the specific angular momentum of gas in the central galaxy to that of the dark matter halo increases significantly with galaxy mass, from 〈j_(gas)〉/〈j_(DM)〉 ∼ 0.1 at M_(star) = 10^(6-7) M_⊙ to 〈j_(gas)〉/〈j_(DM)〉 ∼ 2 at M_(star) = 10^(10–11) M_⊙. The reduced rotational support in the lowest mass galaxies owes to (a) stellar feedback and the UV background suppressing the accretion of high angular momentum gas at late times, and (b) stellar feedback driving large non-circular gas motions. We broadly reproduce the observed scaling relations between galaxy mass, gas rotation velocity, size and angular momentum, but may somewhat underpredict the incidence of disky, high angular momentum galaxies at the lowest observed masses (M_(star) = (10^6–2 × 10^7) M_⊙). Stars form preferentially from low angular momentum gas near the galactic centre and are less rotationally supported than gas. The common assumption that stars follow the same rotation curve as gas thus substantially overestimates the simulated galaxies’ stellar angular momentum, particularly at low masses.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
El-Badry, Kareem0000-0002-6871-1752
Quataert, Eliot0000-0001-9185-5044
Wetzel, Andrew0000-0003-0603-8942
Hopkins, Philip F.0000-0003-3729-1684
Chan, T. K.0000-0003-2544-054X
Boylan-Kolchin, Michael0000-0002-9604-343X
Kereš, Dušan0000-0002-1666-7067
Additional Information:© 2018 Oxford University Press. Accepted 2017 September 22. Received 2017 September 21; in original form 2017 May 30. We thank the anonymous referee for useful comments. We thank Alyson Brooks, Michael Fall, Marla Geha, Chris Hayward, Ryan Leaman, Anne Medling, Matt Orr, Jessica Werk and John Wise for helpful discussions, Alex Richings and Alex Gurvich for help in setting up initial conditions, Peter Nugent for assistance optimizing GIZMO on high-performance computing centres, Luca Cortese for sharing observational data, and Jing Wang for making her data publicly available. KE gratefully acknowledges support from a Berkeley graduate fellowship, a Hellman award for graduate study and an NSF Graduate Research Fellowship. EQ was supported by NASA ATP grant 12-ATP-120183, a Simons Investigator award from the Simons Foundation and the David and Lucile Packard Foundation. 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 grant HST-GO-14734 from STScI. DK was supported by NSF grant AST-1412153 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, and by NASA through grant NNX15AB22G. We ran numerical calculations on the Caltech compute cluster ‘Zwicky’ (NSF MRI award #PHY-0960291). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013) and the sauron colourmap developed by Michele Cappellari (Cappellari 2008).
Group:Moore Center for Theoretical Cosmology and Physics, TAPIR
Funding AgencyGrant Number
University of California, BerkeleyUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Simons FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Caltech-Carnegie FellowshipUNSPECIFIED
Moore Center for Theoretical Cosmology and Physics, CaltechUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:galaxies: dwarf, galaxies: irregular, galaxies: kinematics and dynamics
Record Number:CaltechAUTHORS:20180216-074830560
Persistent URL:
Official Citation:Kareem El-Badry, Eliot Quataert, Andrew Wetzel, Philip F. Hopkins, Daniel R. Weisz, T. K. Chan, Alex Fitts, Michael Boylan-Kolchin, Dušan Kereš, Claude-André Faucher-Giguère, Shea Garrison-Kimmel; Gas kinematics, morphology and angular momentum in the FIRE simulations, Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 2, 11 January 2018, Pages 1930–1955,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84859
Deposited By: Ruth Sustaita
Deposited On:20 Feb 2018 21:06
Last Modified:21 Feb 2018 17:15

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