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Swirls of FIRE: spatially resolved gas velocity dispersions and star formation rates in FIRE-2 disc environments

Orr, Matthew E. and Hayward, Christopher C. and Medling, Anne M. and Gurvich, Alexander B. and Hopkins, Philip F. and Murray, Norman and Pineda, Jorge L. and Faucher-Giguère, Claude-André and Kereš, Dušan and Wetzel, Andrew and Su, Kung-Yi (2020) Swirls of FIRE: spatially resolved gas velocity dispersions and star formation rates in FIRE-2 disc environments. Monthly Notices of the Royal Astronomical Society, 496 (2). pp. 1620-1637. ISSN 0035-8711. doi:10.1093/mnras/staa1619.

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We study the spatially resolved (sub-kpc) gas velocity dispersion (σ)–star formation rate (SFR) relation in the FIRE-2 (Feedback in Realistic Environments) cosmological simulations. We specifically focus on Milky Way-mass disc galaxies at late times (z ≈ 0). In agreement with observations, we find a relatively flat relationship, with σ ≈ 15–30 km s⁻¹ in neutral gas across 3 dex in SFRs. We show that higher dense gas fractions (ratios of dense gas to neutral gas) and SFRs are correlated at constant σ. Similarly, lower gas fractions (ratios of gas to stellar mass) are correlated with higher σ at constant SFR. The limits of the σ–Σ_(SFR) relation correspond to the onset of strong outflows. We see evidence of ‘on-off’ cycles of star formation in the simulations, corresponding to feedback injection time-scales of 10–100 Myr, where SFRs oscillate about equilibrium SFR predictions. Finally, SFRs and velocity dispersions in the simulations agree well with feedback-regulated and marginally stable gas disc (Toomre’s Q = 1) model predictions, and the simulation data effectively rule out models assuming that gas turns into stars at (low) constant efficiency (i.e. 1 per cent per free-fall time). And although the simulation data do not entirely exclude gas accretion/gravitationally powered turbulence as a driver of σ, it appears to be subdominant to stellar feedback in the simulated galaxy discs at z ≈ 0.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Orr, Matthew E.0000-0003-1053-3081
Hayward, Christopher C.0000-0003-4073-3236
Medling, Anne M.0000-0001-7421-2944
Gurvich, Alexander B.0000-0002-6145-3674
Hopkins, Philip F.0000-0003-3729-1684
Pineda, Jorge L.0000-0001-8898-2800
Faucher-Giguère, Claude-André0000-0002-4900-6628
Kereš, Dušan0000-0002-1666-7067
Wetzel, Andrew0000-0003-0603-8942
Su, Kung-Yi0000-0003-1598-0083
Additional Information:© 2020 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 ( Accepted 2020 May 28. Received 2020 May 27; in original form 2019 October 30. Published: 10 June 2020. MEO is grateful for the encouragement of his late father, SRO, in studying astrophysics, and is supported by the National Science Foundation Graduate Research Fellowship under grant no. 1144469. The authors are grateful to the referee for their comments and providing useful suggestions. The Flatiron Institute is supported by the Simons Foundation. Support for AMM is provided by NASA through Hubble Fellowship grant #HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Support for PFH was provided by an Alfred P. Sloan Foundation Research Fellowship, NASA ATP grant NNX14AH35G, and NSF Collaborative Research grant #1411920 and CAREER grant #1455342. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant 17-ATP17-0067, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. DK acknowledges support from the NSF Grant AST-1412153 and Cottrell Scholar Award from the Research Corporation for Science Advancement. EQ was supported by NASA ATP grant 12-ATP12-0183, a Simons Investigator award from the Simons Foundation, and the David and Lucile Packard Foundation. AW received support from NASA, through ATP grant 80NSSC18K1097 and HST grants GO-14734 and AR-15057 from STScI, the Heising-Simons Foundation, and a Hellman Foundation Fellowship.
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Simons FoundationUNSPECIFIED
NASA Hubble FellowshipHST-HF2-51377
Alfred P. Sloan FoundationUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
NASA Hubble FellowshipGO-14734
NASA Hubble FellowshipAR-15057
Heising-Simons FoundationUNSPECIFIED
Hellman FoundationUNSPECIFIED
Subject Keywords:ISM: kinematics and dynamics – galaxies: evolution – galaxies: ISM– galaxies: kinematics and dynamics – galaxies: spiral – galaxies: star formation
Issue or Number:2
Record Number:CaltechAUTHORS:20200903-100107610
Persistent URL:
Official Citation:Matthew E Orr, Christopher C Hayward, Anne M Medling, Alexander B Gurvich, Philip F Hopkins, Norman Murray, Jorge L Pineda, Claude-André Faucher-Giguère, Dušan Kereš, Andrew Wetzel, Kung-Yi Su, Swirls of FIRE: spatially resolved gas velocity dispersions and star formation rates in FIRE-2 disc environments, Monthly Notices of the Royal Astronomical Society, Volume 496, Issue 2, August 2020, Pages 1620–1637,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105237
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 17:50
Last Modified:16 Nov 2021 18:41

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