TY - JOUR
T1 - How Initial Size Governs Core Collapse in Globular Clusters
AU - Kremer, Kyle
AU - Chatterjee, Sourav
AU - Ye, Claire S.
AU - Rodriguez, Carl L.
AU - Rasio, Frederic A.
N1 - Funding Information:
This work was supported by NASA ATP Grant NNX14AP92G and NSF Grant AST-1716762. K.K. acknowledges support by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1324585. S.C. acknowledges support from CIERA, the National Aeronautics and Space Administration through a Chandra Award Number TM5-16004X/NAS8-03060 issued by the Chandra X-ray Observatory Center (operated by the Smithso-nian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060), and Hubble Space Telescope Archival research grant HST-AR-14555.001-A (from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555).
Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.
PY - 2019/1/20
Y1 - 2019/1/20
N2 - Globular clusters (GCs) in the Milky Way exhibit a well-observed bimodal distribution in core radii separating the so-called core-collapsed and non-core-collapsed clusters. Here, we use our Hénon-type Monte Carlo code, CMC, to explore initial cluster parameters that map into this bimodality. Remarkably, we find that by varying the initial size of clusters (specified in our initial conditions in terms of the initial virial radius, r v ) within a relatively narrow range consistent with the measured radii of young star clusters in the local universe (r v ≈ 0.5-5 pc), our models reproduce the variety of present-day cluster properties. Furthermore, we show that stellar-mass black holes (BHs) play an intimate role in this mapping from initial conditions to the present-day structural features of GCs. We identify "best-fit" models for three GCs with known observed BH candidates, NGC 3201, M22, and M10, and show that these clusters harbor populations of ∼50-100 stellar-mass BHs at present. As an alternative case, we also compare our models to the core-collapsed cluster NGC 6752 and show that this cluster likely contains few BHs at present. Additionally, we explore the formation of BH binaries in GCs and demonstrate that these systems form naturally in our models in both detached and mass-transferring configurations with a variety of companion stellar types, including low-mass main-sequence stars, white dwarfs, and sub-subgiants.
AB - Globular clusters (GCs) in the Milky Way exhibit a well-observed bimodal distribution in core radii separating the so-called core-collapsed and non-core-collapsed clusters. Here, we use our Hénon-type Monte Carlo code, CMC, to explore initial cluster parameters that map into this bimodality. Remarkably, we find that by varying the initial size of clusters (specified in our initial conditions in terms of the initial virial radius, r v ) within a relatively narrow range consistent with the measured radii of young star clusters in the local universe (r v ≈ 0.5-5 pc), our models reproduce the variety of present-day cluster properties. Furthermore, we show that stellar-mass black holes (BHs) play an intimate role in this mapping from initial conditions to the present-day structural features of GCs. We identify "best-fit" models for three GCs with known observed BH candidates, NGC 3201, M22, and M10, and show that these clusters harbor populations of ∼50-100 stellar-mass BHs at present. As an alternative case, we also compare our models to the core-collapsed cluster NGC 6752 and show that this cluster likely contains few BHs at present. Additionally, we explore the formation of BH binaries in GCs and demonstrate that these systems form naturally in our models in both detached and mass-transferring configurations with a variety of companion stellar types, including low-mass main-sequence stars, white dwarfs, and sub-subgiants.
KW - globular clusters: general
KW - methods: numerical
KW - stars: black holes
KW - stars: kinematics and dynamics
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U2 - 10.3847/1538-4357/aaf646
DO - 10.3847/1538-4357/aaf646
M3 - Article
AN - SCOPUS:85062024051
VL - 871
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 38
ER -