THE DYNAMICAL EVOLUTION OF STELLAR BLACK HOLES IN GLOBULAR CLUSTERS

By M. Morscher, Bharath Pattabiraman, C. Rodriguez, F. Rasio, S. Umbreit. 2014

163 citations recorded by the source corpus.

Our current understanding of the stellar initial mass function and massive star evolution suggests that young globular clusters (GCs) may have formed hundreds to thousands of stellar-mass black holes (BHs), the remnants of stars with initial masses from ∼20–100 M☉. Birth kicks from supernova explosions may eject some BHs from their birth clusters, but most should be retained. Using a Monte Carlo method we investigate the long-term dynamical evolution of GCs containing large numbers of stellar BHs. We describe numerical results for 42 models, covering a broad range of realistic initial conditions, including up to 1.6 × 106 stars. In almost all models we find that significant numbers of BHs (up to ∼103) are retained all the way to the present. This is in contrast to previous theoretical expectations that most BHs should be ejected dynamically within a few gigayears The main reason for this difference is that core collapse driven by BHs (through the Spitzer “mass segregation instability”) is easily reverted through three-body processes, and involves only a small number of the most massive BHs, while lower-mass BHs remain well-mixed with ordinary stars far from the central cusp. Thus the rapid segregation of stellar BHs does not lead to a long-term physical separation of most BHs into a dynamically decoupled inner core, as often assumed previously. Combined with the recent detections of several BH X-ray binary candidates in Galactic GCs, our results suggest that stellar BHs could still be present in large numbers in many GCs today, and that they may play a significant role in shaping the long-term dynamical evolution and the present-day dynamical structure of many clusters.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4ecb7e59b0669c539962fa5b42533b18f1061f71

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In Astronomy and Astrophysics

1. Michela Mapelli
2. F. Antonini
3. F. Rasio
4. Ilya Mandel
5. D. Holz
6. B. Kocsis
7. N. Giacobbo
8. S. Banerjee

Citations in the corpus

• DYNAMICAL FORMATION OF THE GW150914 BINARY BLACK HOLE (2016, background): “This result is surprising, given that three-body binary formation is expected to be the dominant mechanism for creating new BBHs in the cores of GCs (Morscher et al. 2015).”
• The dragon simulations: globular cluster evolution with a million stars (2016, methodology): “Morscher et al. (2015) suggest that the latter can provide better fits.”
• Constraining Formation Models of Binary Black Holes with Gravitational-wave Observations (2017, background): “…according to where i is the index of the list of black holes, sorted in order of decreasing mass. Equation (4) is physically motivated by the fact that globular clusters preferentially eject the most massive black holes first, continuing to eject black holes until depletion (Morscher et al. 2015).”
• Rapid and Bright Stellar-mass Binary Black Hole Mergers in Active Galactic Nuclei (2016, background): “…in dense stellar systems including globular clusters and galactic nuclei (Portegies Zwart & McMillan 2002; Miller & Hamilton 2002; Portegies Zwart et al. 2004; O’Leary et al. 2009; Kocsis & Levin 2012; Naoz et al. 2013; Antonini et al. 2014; Antognini et al. 2014; Morscher et al. 2015).”
• MERGING BLACK HOLE BINARIES IN GALACTIC NUCLEI: IMPLICATIONS FOR ADVANCED-LIGO DETECTIONS (2016, background): “6 in Morscher et al. 2015).”
• Rates of compact object coalescences (2021, background): “…has been explored by Sigurdsson and Hernquist (1993); Kulkarni et al. (1993); Portegies Zwart and McMillan (2000); O’Leary et al. (2006); Banerjee et al. (2010); Downing et al. (2011); Morscher et al. (2015) through a mix of numerical gravitational experiments and semi-analytical estimates.”
• BLACK HOLE MERGERS AND BLUE STRAGGLERS FROM HIERARCHICAL TRIPLES FORMED IN GLOBULAR CLUSTERS (2015, methodology): “In this paper we use a Monte Carlo code to simulate the long-term evolution of GCs (Morscher et al. 2015), and identify all triple systems formed during the cluster evolution.”
• Massive black hole binaries from runaway collisions: the impact of metallicity (2016, background): “…(5 − 15 M⊙), despite the efficiency of dynamical exchanges (see also Downing et al. 2010, 2011; O’Leary et al. 2006; Sadowski et al. 2008; Clausen et al. 2013; Morscher et al. 2015; Rodriguez et al. 2015; Amaro-Seoane & Chen 2015; O’Leary et al. 2016; Chatterjee et al. 2016 for other predictions).”
• ASTROPHYSICAL IMPLICATIONS OF THE BINARY BLACK HOLE MERGER GW150914 (2016, methodology): “Morscher et al. (2015) and Rodriguez et al. (2016) further accounted for a population of globular clusters with varying cluster properties (mass, density, and metallicity).”
• Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation (2016, methodology): “This “self-regulation” causes the BH population to decline but exponentially; see below and also Morscher et al. (2015).”