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Live Fast, Die Young: GMC lifetimes in the FIRE cosmological simulations of Milky Way-mass galaxies

Benincasa, Samantha M. and Loebman, Sarah R. and Wetzel, Andrew and Hopkins, Philip F. and Murray, Norman and Bellardini, Matthew A. and Faucher-Giguère, Claude-André and Guszejnov, Dávid and Orr, Matthew (2020) Live Fast, Die Young: GMC lifetimes in the FIRE cosmological simulations of Milky Way-mass galaxies. Monthly Notices of the Royal Astronomical Society, 497 (3). pp. 3993-3999. ISSN 0035-8711. doi:10.1093/mnras/staa2116.

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We present the first measurement of the lifetimes of giant molecular clouds (GMCs) in cosmological simulations at z = 0, using the Latte suite of FIRE-2 simulations of Milky Way (MW) mass galaxies. We track GMCs with total gas mass ≳10⁵ M⊙ at high spatial (∼1 pc), mass (7100 M⊙), and temporal (1 Myr) resolution. Our simulated GMCs are consistent with the distribution of masses for massive GMCs in the MW and nearby galaxies. We find GMC lifetimes of 5–7 Myr, or 1–2 freefall times, on average, with less than 2 per cent of clouds living longer than 20 Myr. We find decreasing GMC lifetimes with increasing virial parameter, and weakly increasing GMC lifetimes with galactocentric radius, implying that environment affects the evolutionary cycle of GMCs. However, our GMC lifetimes show no systematic dependence on GMC mass or amount of star formation. These results are broadly consistent with inferences from the literature and provide an initial investigation into ultimately understanding the physical processes that govern GMC lifetimes in a cosmological setting.

Item Type:Article
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URLURL TypeDescription Paper ItemPYTHON packages ItemPYTHON packages
Benincasa, Samantha M.0000-0003-4826-9079
Loebman, Sarah R.0000-0003-3217-5967
Wetzel, Andrew0000-0003-0603-8942
Hopkins, Philip F.0000-0003-3729-1684
Faucher-Giguère, Claude-André0000-0002-4900-6628
Guszejnov, Dávid0000-0001-5541-3150
Orr, Matthew0000-0003-1053-3081
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 July 7. Received 2020 July 7; in original form 2019 November 4; Published: 24 July 2020. The authors thank the scientific editor, Joop Schaye, and the anonymous referee whose insight greatly improved the work presented here. This research made use of ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013, 2018). SB, AW, and MB were supported by a Hellman Fellowship, the Heising-Simons Foundation, and NASA, through ATP grant 80NSSC18K1097 and HST grants GO-14734 and AR-15057 from STScI. SRL was supported by NASA through Hubble Fellowship grant #HST-JF2-51395.001-A awarded by STScI. NM was supported by NSERC. PFH was supported by NSF grants 1715847 and 1911233, CAREER grant 1455342, and NASA grants 80NSSC18K0562 and JPL 1589742. DG was supported by the Harlan J. Smith McDonald Observatory Postdoctoral Fellowship. CAFG was supported by NSF grants AST-1517491, AST-1715216, CAREER award AST-1652522, by NASA grant 17-ATP17-0067, by STScI grant HST-GO-14681.011, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. We ran these simulations and analysis using allocations from: XSEDE AST130039 and AST140064; Blue Waters PRAC NSF.1455342 supported by NSF; and NASA HEC SMD-16-7324, SMD-16-7592, SMD-17-1289, SMD-17-1375, SMD-18-2189. Data Availability: Single simulation snapshots at z = 0 are available for m12i, m12f, and m12m at Our analysis made use of the publicly available PYTHON packages and
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Hellman FellowshipUNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
NASA Hubble FellowshipGO-14734
NASA Hubble FellowshipAR-15057
Space Telescope Science InstituteUNSPECIFIED
NASA Hubble FellowshipHST-JF2-51395.001-A
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Harlan J. Smith McDonald ObservatoryUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Subject Keywords:methods: numerical – ISM: clouds – ISM: evolution
Issue or Number:3
Record Number:CaltechAUTHORS:20200310-100838684
Persistent URL:
Official Citation:Samantha M Benincasa, Sarah R Loebman, Andrew Wetzel, Philip F Hopkins, Norman Murray, Matthew A Bellardini, Claude-André Faucher-Giguère, Dávid Guszejnov, Matthew Orr, Live fast, die young: GMC lifetimes in the FIRE cosmological simulations of Milky Way mass galaxies, Monthly Notices of the Royal Astronomical Society, Volume 497, Issue 3, September 2020, Pages 3993–3999,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101818
Deposited By: Tony Diaz
Deposited On:10 Mar 2020 17:44
Last Modified:16 Nov 2021 18:06

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