Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies
Abstract
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.
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 (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_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 http://www.tapir.caltech.edu/∼phopkins/Site/GIZMO.html. Additional data including simulation snapshots, initial conditions, and derived data products are available at http://fire.northwestern.edu/data/.Attached Files
Published - staa2578.pdf
Submitted - 2005.12916.pdf
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Additional details
- Alternative title
- Pressure balance in the multiphase ISM of cosmologically simulated disk galaxies
- Eprint ID
- 104100
- Resolver ID
- CaltechAUTHORS:20200626-150120381
- NSF Graduate Research Fellowship
- DGE-1842165
- NSF Graduate Research Fellowship
- DGE-0948017
- NSF Graduate Research Fellowship
- DGE-145000
- NSF
- OCI-0725070
- NSF
- ACI-1238993
- NSF
- AST-1412836
- NSF
- AST-1517491
- NSF
- AST-1715216
- NSF
- AST-1652522
- NASA
- NNX15AB22G
- NASA
- 17-ATP17-0067
- NASA
- HST-GO-14681.011
- NASA
- HST-GO-14268.022-A
- NASA
- HST-AR-14293.001-A
- Cottrell Scholar of Research Corporation
- European Research Council (ERC)
- 609412
- Science and Technology Facilities Council (STFC)
- ST/P000541/1
- Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)
- Science and Technology Facilities Council (STFC)
- ST/T000244/1
- NSF
- AST-1715101
- NASA
- 80NSSC18K1097
- NASA
- HST-GO-14734
- NASA
- HST-AR-15057
- NASA
- HST-AR-15809
- NASA
- HST-GO-15902
- Heising-Simons Foundation
- Hellman Fellowship
- NASA Hubble Fellowship
- HST-JF2-51395.001-A
- NASA
- NAS5-26555
- Simons Foundation
- Canada Research Chairs Program
- NSF
- TG-AST120025
- NSF
- TG-AST140023
- NSF
- TG-AST130039
- NSF
- TG-AST140064
- NSF
- OAC-1713353
- NASA
- SMD16-7592
- NASA
- SMD-16-7561
- NASA
- SMD-17-1204
- NASA
- SMD-16-7324
- NASA
- SMD-17-1375
- Created
-
2020-06-29Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, TAPIR