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Interacting galaxies on FIRE-2: the connection between enhanced star formation and interstellar gas content

Moreno, Jorge and Torrey, Paul and Ellison, Sara L. and Patton, David R. and Hopkins, Philip F. and Bueno, Michael and Hayward, Christopher C. and Narayanan, Desika and Kereš, Dušan and Bluck, Asa F. L. and Hernquist, Lars (2019) Interacting galaxies on FIRE-2: the connection between enhanced star formation and interstellar gas content. Monthly Notices of the Royal Astronomical Society, 485 (1). pp. 1320-1338. ISSN 0035-8711. doi:10.1093/mnras/stz417.

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We present a comprehensive suite of high-resolution (parsec-scale), idealized (non-cosmological) galaxy merger simulations (24 runs, stellar mass ratio ∼2.5:1) to investigate the connection between interaction-induced star formation and the evolution of the interstellar medium (ISM) in various temperature–density regimes. We use the GIZMO code and the second version of the ‘Feedback in Realistic Environments’ model (FIRE-2), which captures the multiphase structure of the ISM. Our simulations are designed to represent galaxy mergers in the local Universe. In this work, we focus on the ‘galaxy-pair period’ between first and second pericentric passage. We split the ISM into four regimes: hot, warm, cool, and cold-dense, motivated by the hot, ionized, atomic and molecular gas phases observed in real galaxies. We find that, on average, interactions enhance the star formation rate of the pair (⁠∼30 per cent, merger-suite sample average) and elevate their cold-dense gas content (⁠∼18 per cent⁠). This is accompanied by a decrease in warm gas (⁠∼11 per cent), a negligible change in cool gas (⁠∼4 per cent increase), and a substantial increase in hot gas (⁠∼400 per cent⁠). The amount of cold-dense gas with densities above 1000 cm^(−3) (the cold ultra-dense regime) is elevated significantly (⁠∼240 per cent⁠), but only accounts for ∼0.15 per cent (on average) of the cold-dense gas budget.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Torrey, Paul0000-0002-5653-0786
Ellison, Sara L.0000-0002-1768-1899
Hopkins, Philip F.0000-0003-3729-1684
Hayward, Christopher C.0000-0003-4073-3236
Narayanan, Desika0000-0002-7064-4309
Kereš, Dušan0000-0002-1666-7067
Hernquist, Lars0000-0001-6950-1629
Additional Information:© 2019 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 2019 January 30. Received 2019 January 29; in original form 2018 May 7. Published: 11 February 2019. The computations in this paper were run on the Odyssey cluster supported by the Faculty of Arts and Sciences, Division of Science, Research Computing Group at Harvard University. Support for JM is provided by the National Science Foundation (Award Number 1516374), and by the Harvard Institute for Theory and Computation, through their Visiting Scholars Program. The Flatiron Institute is supported by the Simons Foundation. DK is supported by the National Science Foundation (Award Number 1715101), and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. We thank Jillian Scudder and George Privon for illuminating discussions, Jason Brown for helping us create our galaxy mergers website, and the two anonymous reviewers, whose insightful suggestions improved the quality of this paper. JM thanks Dra. Nicole Cabrera Salazar (Movement Consulting) for co-mentoring a large group of outstanding undergraduate students of colour, including MB. We honour the invaluable labour of the maintenance and clerical staff at our institutions, whose contributions make our scientific discoveries a reality. This research was conducted on Tongva-Gabrielino Indigenous land.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
Harvard UniversityUNSPECIFIED
Simons FoundationUNSPECIFIED
Research CorporationUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: interactions – galaxies: star formation – galaxies: ISM
Issue or Number:1
Record Number:CaltechAUTHORS:20190524-072411270
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Official Citation:Jorge Moreno, Paul Torrey, Sara L Ellison, David R Patton, Philip F Hopkins, Michael Bueno, Christopher C Hayward, Desika Narayanan, Dušan Kereš, Asa F L Bluck, Lars Hernquist, Interacting galaxies on FIRE-2: the connection between enhanced star formation and interstellar gas content, Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 1, May 2019, Pages 1320–1338,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95773
Deposited By: Tony Diaz
Deposited On:24 May 2019 14:40
Last Modified:16 Nov 2021 17:15

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