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Compact Object Modeling in the Globular Cluster 47 Tucanae

Ye, Claire S. and Kremer, Kyle and Rodriguez, Carl L. and Rui, Nicholas Z. and Weatherford, Newlin C. and Chatterjee, Sourav and Fragione, Giacomo and Rasio, Frederic A. (2022) Compact Object Modeling in the Globular Cluster 47 Tucanae. Astrophysical Journal, 931 (2). Art. No. 84. ISSN 0004-637X. doi:10.3847/1538-4357/ac5b0b.

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The globular cluster 47 Tucanae (47 Tuc) is one of the most massive star clusters in the Milky Way and is exceptionally rich in exotic stellar populations. For several decades it has been a favorite target of observers, and yet it is computationally very challenging to model because of its large number of stars (N ≳ 10⁶) and high density. Here we present detailed and self-consistent 47 Tuc models computed with the Cluster Monte Carlo code (CMC). The models include all relevant dynamical interactions coupled to stellar and binary evolution, and reproduce various observations, including the surface brightness and velocity dispersion profiles, pulsar accelerations, and numbers of compact objects. We show that the present properties of 47 Tuc are best reproduced by adopting an initial stellar mass function that is both bottom-heavy and top-light relative to standard assumptions (as in, e.g., Kroupa 2001), and an initial Elson profile (Elson et al. 1987) that is overfilling the cluster's tidal radius. We include new prescriptions in CMC for the formation of binaries through giant star collisions and tidal captures, and we show that these mechanisms play a crucial role in the formation of neutron star binaries and millisecond pulsars in 47 Tuc; our best-fit model contains ∼50 millisecond pulsars, 70% of which are formed through giant collisions and tidal captures. Our models also suggest that 47 Tuc presently contains up to ∼200 stellar-mass black holes, ∼5 binary black holes, ∼15 low-mass X-ray binaries, and ∼300 cataclysmic variables.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ye, Claire S.0000-0001-9582-881X
Kremer, Kyle0000-0002-4086-3180
Rodriguez, Carl L.0000-0003-4175-8881
Rui, Nicholas Z.0000-0002-1884-3992
Weatherford, Newlin C.0000-0002-9660-9085
Chatterjee, Sourav0000-0002-3680-2684
Fragione, Giacomo0000-0002-7330-027X
Rasio, Frederic A.0000-0002-7132-418X
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 October 8; revised 2022 March 2; accepted 2022 March 3; published 2022 May 26. We thank Sebastian Kamann, Stefan Dreizler, and the anonymous referee for helpful discussions and suggestions on the manuscript. This work was supported by NSF grants AST-1716762 and AST-2108624 at Northwestern University, and by NSF grant AST-2009916 at Carnegie Mellon University. K.K. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001751. C.R. acknowledges support from a New Investigator Research Grant from the Charles E. Kaufman Foundation. N.Z.R. acknowledges support from the Dominic Orr Graduate Fellowship at Caltech and the National Science Foundation Graduate Research Fellowship under grant No. DGE1745301. N.C.W. acknowledges support from the CIERA Riedel Family Graduate Fellowship. S.C. acknowledges support from the Department of Atomic Energy, Government of India, under project No. 12-R&D-TFR-5.02-0200. G.F. and F.A.R. acknowledge support from NASA grant 80NSSC21K1722. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. Software: CMC (Joshi et al. 2000, 2001; Fregeau et al. 2003; Fregeau & Rasio 2007; Chatterjee et al. 2010; Umbreit et al. 2012; Chatterjee et al. 2013; Pattabiraman et al. 2013; Morscher et al. 2015; Rodriguez et al. 2016, 2022), Fewbody (Fregeau et al. 2004), COSMIC (Breivik et al. 2020).
Funding AgencyGrant Number
NSF Astronomy and Astrophysics FellowshipAST-2001751
Charles E. Kaufman FoundationUNSPECIFIED
Dominic Orr Graduate FellowshipUNSPECIFIED
NSF Graduate Research FellowshipDGE-1745301
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Department of Atomic Energy (India)12-R&D-TFR-5.02-0200
Northwestern UniversityUNSPECIFIED
Subject Keywords:Star clusters; Astronomical simulations; N-body simulations; Compact objects
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Star clusters (1567); Astronomical simulations (185); N-body simulations (1083); Compact objects (288)
Record Number:CaltechAUTHORS:20220718-155886300
Persistent URL:
Official Citation:Claire S. Ye et al 2022 ApJ 931 84
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115668
Deposited By: Tony Diaz
Deposited On:20 Jul 2022 16:55
Last Modified:20 Jul 2022 16:55

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