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Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies

Ma, Xiangcheng and Grudić, Michael Y. and Quataert, Eliot and Hopkins, Philip F. and Faucher-Giguère, Claude-André and Boylan-Kolchin, Michael and Wetzel, Andrew and Kim, Ji-Hoon and Murray, Norman and Kereš, Dušan (2020) Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies. Monthly Notices of the Royal Astronomical Society, 493 (3). pp. 4315-4332. ISSN 0035-8711.

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We report the formation of bound star clusters in a sample of high-resolution cosmological zoom-in simulations of z ≥ 5 galaxies from the Feedback In Realistic Environments project. We find that bound clusters preferentially form in high-pressure clouds with gas surface densities over 10⁴M⊙pc⁻²⁠, where the cloud-scale star formation efficiency is near unity and young stars born in these regions are gravitationally bound at birth. These high-pressure clouds are compressed by feedback-driven winds and/or collisions of smaller clouds/gas streams in highly gas-rich, turbulent environments. The newly formed clusters follow a power-law mass function of dN/dM ∼ M⁻². The cluster formation efficiency is similar across galaxies with stellar masses of ∼10⁷–10¹⁰M⊙ at z ≥ 5. The age spread of cluster stars is typically a few Myr and increases with cluster mass. The metallicity dispersion of cluster members is ∼0.08 dex in [Z/H] and does not depend on cluster mass significantly. Our findings support the scenario that present-day old globular clusters (GCs) were formed during relatively normal star formation in high-redshift galaxies. Simulations with a stricter/looser star formation model form a factor of a few more/fewer bound clusters per stellar mass formed, while the shape of the mass function is unchanged. Simulations with a lower local star formation efficiency form more stars in bound clusters. The simulated clusters are larger than observed GCs due to finite resolution. Our simulations are among the first cosmological simulations that form bound clusters self-consistently in a wide range of high-redshift galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ma, Xiangcheng0000-0001-8091-2349
Grudić, Michael Y.0000-0002-1655-5604
Quataert, Eliot0000-0001-9185-5044
Hopkins, Philip F.0000-0003-3729-1684
Faucher-Giguère, Claude-André0000-0002-4900-6628
Boylan-Kolchin, Michael0000-0002-9604-343X
Wetzel, Andrew0000-0003-0603-8942
Kim, Ji-Hoon0000-0003-4464-1160
Kereš, Dušan0000-0002-1666-7067
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 February 18. Received 2020 February 13; in original form 2019 June 26. Published: 21 February 2020. We acknowledge our referee, Oleg Gnedin, for a constructive report that helps us correct a few errors and inaccurate statements and improve the clarity of this paper. We also thank many colleagues, especially Paul Shapiro and Hui Li, for sending us helpful comments and discussions after this paper appeared on arXiv. The simulations used in this paper were run on XSEDE computational resources (allocations TG-AST120025, TG-AST130039, TG-AST140023, TG-AST140064, and TG-AST190028). This work was supported in part by a Simons Investigator Award from the Simons Foundation (EQ) and by NSF grant AST-1715070. EQ thanks the Princeton Astrophysical Sciences department and the theoretical astrophysics group and Moore Distinguished Scholar program at Caltech for their hospitality and support. MG and PFH were supported by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant 17-ATP17-0067, by STScI through grant HST-GO-14681.011, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. MBK acknowledges support from NSF grant AST-1517226 and CAREER grant AST-1752913 and from NASA grants NNX17AG29G and HST-AR-14282, HST-AR-14554, HST-AR-15006, and HST-GO-14191 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. AW was supported by NASA, through ATP grant 80NSSC18K1097 and HST grants GO-14734 and AR-15057 from STScI. DK was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement.
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Simons FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
NASA Hubble FellowshipGO-14734
NASA Hubble FellowshipAR-15057
Subject Keywords:galaxies: evolution – galaxies: formation – galaxies: high-redshift – cosmology: theory – star clusters: general
Issue or Number:3
Record Number:CaltechAUTHORS:20190726-093900885
Persistent URL:
Official Citation:Xiangcheng Ma, Michael Y Grudić, Eliot Quataert, Philip F Hopkins, Claude-André Faucher-Giguère, Michael Boylan-Kolchin, Andrew Wetzel, Ji-hoon Kim, Norman Murray, Dušan Kereš, Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies, Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 3, April 2020, Pages 4315–4332,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97438
Deposited By: Tony Diaz
Deposited On:26 Jul 2019 17:25
Last Modified:30 Apr 2020 17:56

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