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What FIREs up star formation: the emergence of the Kennicutt–Schmidt law from feedback

Orr, Matthew E. and Hayward, Christopher C. and Hopkins, Philip F. and Chan, T. K. and Faucher-Giguère, Claude-André and Feldmann, Robert and Kereš, Dušan and Murray, Norman and Quataert, Eliot (2018) What FIREs up star formation: the emergence of the Kennicutt–Schmidt law from feedback. Monthly Notices of the Royal Astronomical Society, 478 (3). pp. 3653-3673. ISSN 0035-8711.

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We present an analysis of the global and spatially resolved Kennicutt–Schmidt (KS) star formation relation in the FIRE (Feedback In Realistic Environments) suite of cosmological simulations, including haloes with z = 0 masses ranging from 10^(10) to 10^(13) M_⊙. We show that the KS relation emerges and is robustly maintained due to the effects of feedback on local scales regulating star-forming gas, independent of the particular small-scale star formation prescriptions employed. We demonstrate that the time-averaged KS relation is relatively independent of redshift and spatial averaging scale, and that the star formation rate surface density is weakly dependent on metallicity and inversely dependent on orbital dynamical time. At constant star formation rate surface density, the ‘cold and dense’ gas surface density (gas with T < 300 K and n > 10 cm^(−3), used as a proxy for the molecular gas surface density) of the simulated galaxies is ∼0.5 dex less than observed at ∼kpc scales. This discrepancy may arise from underestimates of the local column density at the particle-scale for the purposes of shielding in the simulations. Finally, we show that on scales larger than individual giant molecular clouds, the primary condition that determines whether star formation occurs is whether a patch of the galactic disc is thermally Toomre-unstable (not whether it is self-shielding): once a patch can no longer be thermally stabilized against fragmentation, it collapses, becomes self-shielding, cools, and forms stars, regardless of epoch or environment.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Orr, Matthew E.0000-0003-1053-3081
Hayward, Christopher C.0000-0003-4073-3236
Hopkins, Philip F.0000-0003-3729-1684
Chan, T. K.0000-0003-2544-054X
Feldmann, Robert0000-0002-1109-1919
Kereš, Dušan0000-0002-1666-7067
Quataert, Eliot0000-0001-9185-5044
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 ( Accepted 2018 May 10. Received 2018 May 10; in original form 2017 January 6. MEO is grateful for the encouragement of his late father, SRO, in studying astrophysics, and for many helpful discussions with A. Wetzel, J. Schaye, S. Dib, and I. Escala. We are grateful to the anonymous referee for providing us with constructive comments and suggestions, which have significantly improved the work. This research has made use of NASA’s Astrophysics Data System. MEO was supported by the National Science Foundation Graduate Research Fellowship under grant no. 1144469. CCH is grateful to the Gordon and Betty Moore Foundation for financial support. The Flatiron Institute is supported by the Simons Foundation. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. Numerical calculations were run on the Caltech compute cluster ‘Zwicky’ (NSF MRI award #PHY-0960291) and allocations TG-AST120025, and TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF. CAFG was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by STScI through grants HST-AR-14293.001-A and HST-GO-14268.022-A. RF was supported by the Swiss National Science Foundation (grant no. 157591). 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.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Gordon and Betty Moore FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Swiss National Science Foundation (SNSF)157591
Cottrell Scholar of Research CorporationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:instabilities, opacity, methods: numerical, galaxies: evolution, galaxies: formation, galaxies: star formation
Record Number:10.1093/mnras/sty1241
Persistent URL:
Official Citation:Matthew E Orr, Christopher C Hayward, Philip F Hopkins, T K Chan, Claude-André Faucher-Giguère, Robert Feldmann, Dušan Kereš, Norman Murray, Eliot Quataert; What FIREs up star formation: the emergence of the Kennicutt–Schmidt law from feedback, Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 3, 21 August 2018, Pages 3653–3673,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87355
Deposited By: George Porter
Deposited On:26 Jun 2018 21:49
Last Modified:26 Jun 2018 21:49

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