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Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies

Gurvich, Alexander B. and Faucher-Giguère, Claude-André and Richings, Alexander J. and Hopkins, Philip F. and Grudić, Michael Y. and Hafen, Zachary and Wellons, Sarah and Stern, Jonathan and Quataert, Eliot and Chan, T. K. and Orr, Matthew E. and Kereš, Dušan and Wetzel, Andrew and Hayward, Christopher C. and Loebman, Sarah R. and Murray, Norman (2020) Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies. Monthly Notices of the Royal Astronomical Society, 498 (3). pp. 3664-3683. ISSN 0035-8711. doi:10.1093/mnras/staa2578.

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Pressure balance plays a central role in models of the interstellar medium (ISM), but whether and how pressure balance is realized in a realistic multiphase ISM is not yet well understood. We address this question by using a set of FIRE-2 cosmological zoom-in simulations of Milky Way-mass disc galaxies, in which a multiphase ISM is self-consistently shaped by gravity, cooling, and stellar feedback. We analyse how gravity determines the vertical pressure profile as well as how the total ISM pressure is partitioned between different phases and components (thermal, dispersion/turbulence, and bulk flows). We show that, on average and consistent with previous more idealized simulations, the total ISM pressure balances the weight of the overlying gas. Deviations from vertical pressure balance increase with increasing galactocentric radius and with decreasing averaging scale. The different phases are in rough total pressure equilibrium with one another, but with large deviations from thermal pressure equilibrium owing to kinetic support in the cold and warm phases, which dominate the total pressure near the mid-plane. Bulk flows (e.g. inflows and fountains) are important at a few disc scale heights, while thermal pressure from hot gas dominates at larger heights. Overall, the total mid-plane pressure is well-predicted by the weight of the disc gas and we show that it also scales linearly with the star formation rate surface density (Σ_(SFR)). These results support the notion that the Kennicutt–Schmidt relation arises because Σ_(SFR) and the gas surface density (Σ_g) are connected via the ISM mid-plane pressure.

Item Type:Article
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URLURL TypeDescription Paper ItemGIZMO code ItemAdditional data
Gurvich, Alexander B.0000-0002-6145-3674
Faucher-Giguère, Claude-André0000-0002-4900-6628
Richings, Alexander J.0000-0003-0502-9235
Hopkins, Philip F.0000-0003-3729-1684
Grudić, Michael Y.0000-0002-1655-5604
Hafen, Zachary0000-0001-7326-1736
Wellons, Sarah0000-0002-3977-2724
Stern, Jonathan0000-0002-7541-9565
Quataert, Eliot0000-0001-9185-5044
Chan, T. K.0000-0003-2544-054X
Orr, Matthew E.0000-0003-1053-3081
Kereš, Dušan0000-0002-1666-7067
Wetzel, Andrew0000-0003-0603-8942
Hayward, Christopher C.0000-0003-4073-3236
Alternate Title:Pressure balance in the multiphase ISM of cosmologically simulated disk galaxies
Additional Information:© The Author(s) 2020. 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 August 15. Received 2020 August 10; in original form 2020 May 25. Published: 26 August 2020. The authors thank the anonymous referee whose helpful comments improved the quality of this manuscript. AG is grateful to Chang-Goo Kim for very useful discussions regarding the analysis of disc equilibrium in simulations; Samantha Benincasa and Victor Robles for their helpful comments that improved the quality of this paper; and Bridget Haas for her unwavering support and encouragement during the course of the project. ABG was supported by a National Science Foundation Graduate Research Fellowship Program under grant DGE-1842165 and was additionally supported by the NSF under grants DGE-0948017 and DGE-145000, and from Blue Waters as a graduate fellow which is itself supported by the NSF (awards OCI-0725070 and ACI-1238993). CAFG was supported by NSF through grants AST-1412836, AST-1517491, AST-1715216, and CAREER award AST1652522, by NASA through grants NNX15AB22G and 17-ATP17-0067, by STScI through grants HST-GO-14681.011, HST-GO-14268.022-A, and HST-AR-14293.001-A, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. AJR was supported by a COFUND/Durham Junior Research Fellowship under EU grant 609412 and by the Science and Technology Facilities Council [ST/P000541/1]. MYG, SW, and JS are supported as a CIERA Fellows by the CIERA Postdoctoral Fellowship Program (Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University). TKC was supported by the Science and Technology Facilities Council astronomy consolidated grant ST/T000244/1. DK was supported by NSF grant AST-1715101 and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. AW received support from NASA through ATP grant 80NSSC18K1097 and HST grants GO-14734, AR-15057, AR-15809, and GO-15902 from STScI; the Heising-Simons Foundation; and a Hellman Fellowship. Support for SRL was provided by NASA through Hubble Fellowship grant HST-JF2-51395.001-A 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. The Flatiron Institute is supported by the Simons Foundation. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program. Numerical calculations were run on the Quest computing cluster at Northwestern University; the Wheeler computing cluster at Caltech; XSEDE allocations TG-AST120025, TG-AST140023, TG-AST130039, and TG-AST140064; Blue Waters PRAC allocation NSF.1713353; and NASA HEC allocation SMD16-7592, SMD-16-7561, SMD-17-1204, SMD-16-7324, and SMD-17-1375. Data Availability: The data supporting the plots within this article are available on reasonable request to the corresponding author. A public version of the GIZMO code is available at∼phopkins/Site/GIZMO.html. Additional data including simulation snapshots, initial conditions, and derived data products are available at
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1842165
NSF Graduate Research FellowshipDGE-0948017
NSF Graduate Research FellowshipDGE-145000
Cottrell Scholar of Research CorporationUNSPECIFIED
European Research Council (ERC)609412
Science and Technology Facilities Council (STFC)ST/P000541/1
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/T000244/1
Heising-Simons FoundationUNSPECIFIED
Hellman FellowshipUNSPECIFIED
NASA Hubble FellowshipHST-JF2-51395.001-A
Simons FoundationUNSPECIFIED
Canada Research Chairs ProgramUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: formation – galaxies: ISM– galaxies: star formation – cosmology: theory
Issue or Number:3
Record Number:CaltechAUTHORS:20200626-150120381
Persistent URL:
Official Citation:Alexander B Gurvich, Claude-André Faucher-Giguère, Alexander J Richings, Philip F Hopkins, Michael Y Grudić, Zachary Hafen, Sarah Wellons, Jonathan Stern, Eliot Quataert, T K Chan, Matthew E Orr, Dušan Kereš, Andrew Wetzel, Christopher C Hayward, Sarah R Loebman, Norman Murray, Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies, Monthly Notices of the Royal Astronomical Society, Volume 498, Issue 3, November 2020, Pages 3664–3683,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104100
Deposited By: George Porter
Deposited On:29 Jun 2020 17:43
Last Modified:16 Nov 2021 18:28

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