The dragon simulations: globular cluster evolution with a million stars

By Long Wang, Rainer Spurzem, S. Aarseth, M. Giersz, A. Askar, Peter Berczik, T. Naab, R. Schadow, M. B. N. Kouwenhoven. 2016

180 citations recorded by the source corpus.

Introducing the dragon simulation project, we present direct N-body simulations of four massive globular clusters (GCs) with 106 stars and 5 per cent primordial binaries at a high level of accuracy and realism. The GC evolution is computed with nbody6++gpu and follows the dynamical and stellar evolution of individual stars and binaries, kicks of neutron stars and black holes (BHs), and the effect of a tidal field. We investigate the evolution of the luminous (stellar) and dark (faint stars and stellar remnants) GC components and create mock observations of the simulations (i.e. photometry, colour–magnitude diagrams, surface brightness and velocity dispersion profiles). By connecting internal processes to observable features, we highlight the formation of a long-lived ‘dark’ nuclear subsystem made of BHs, which results in a two-component structure. The inner core is dominated by the BH subsystem and experiences a core-collapse phase within the first Gyr. It can be detected in the stellar (luminous) line-of-sight velocity dispersion profiles. The outer extended core – commonly observed in the (luminous) surface brightness profiles – shows no collapse features and is continuously expanding. We demonstrate how a King model fit to observed clusters might help identify the presence of post core-collapse BH subsystems. For global observables like core and half-mass radii, the direct simulations agree well with Monte Carlo models. Variations in the initial mass function can result in significantly different GC properties (e.g. density distributions) driven by varying amounts of early mass-loss and the number of forming BHs. (Less)

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0fbbed49b8dfe595471cfe9897a7e07a417501d0

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In Astronomy and Astrophysics

1. Michela Mapelli
2. N. Giacobbo
3. Mario Spera
4. F. Rasio
5. S. Banerjee
6. H. Baumgardt
7. B. Kocsis
8. C. Rodriguez

In Instrumentation

1. Michael Hilker
2. H. Baumgardt
3. M. Giersz
4. Michela Mapelli
5. F. Rasio
6. Mario Spera
7. C. Rodriguez
8. S. Banerjee

Citations in the corpus

• Constraining Stellar-mass Black Hole Mergers in AGN Disks Detectable with LIGO (2017, background): “…naturally in the field (Belczynski et al. 2010; deMink & Mandel 2016) and in globular clusters (Breen & Heggie 2013; Rodriguez et al. 2016a, 2018; Wang et al. 2016), they are more likely to form in regions with concentrations of BHs, such as galactic nuclear star clusters (Hopman & Alexander…”
• MOCCA-SURVEY Database - I. Coalescing binary black holes originating from globular clusters (2016, methodology): “…limited clusters based on Fukushige & Heggie (2000). mocca has been extensively tested against the results of Nbody simulations of star cluster models comprising of thirty thousand to one million stars (Giersz et al. 2013; Heggie 2014; Wang et al. 2016; Mapelli 2016, and references therein).”
• N-body modelling of globular clusters: masses, mass-to-light ratios and intermediate-mass black holes (2016, methodology): “…to test how well our fitting method can reproduce star cluster masses from their surface density and velocity dispersion profiles we apply our models to the N-body simulations uf13 and uf14 from Lamers, Baumgardt & Gieles (2013) and models D1 and D2 from the DRAGON simulation (Wang et al. 2016a).”
• A catalogue of masses, structural parameters, and velocity dispersion profiles of 112 Milky Way globular clusters (2018, methodology): “…of the computer codes has allowed to perform simulations of globular clusters with up to 106 stars through either direct N-body (Heggie 2014; Wang et al. 2016) or Monte Carlo simulations (e.g. Giersz & Heggie 2011; Askar et al. 2017), meaning that a detailed comparison of observations and…”
• Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation (2016, background): “It is also worth recalling the “Dragon Simulations” (Wang et al. 2016) in this context, where relatively extended, ≈ 3− 8 pc-sized, much more massive clusters of N ≈ 106 stars (they can also be taken as representatives of galactic nuclear clusters) are evolved for nearly a Hubble time and the…”
• Modeling Dense Star Clusters in the Milky Way and Beyond with the CMC Cluster Catalog (2019, background): “…are now well understood, and several in-depth studies have achieved consensus (Merritt et al. 2004; Mackey et al. 2007, 2008; Breen & Heggie 2013; Peuten et al. 2016; Wang et al. 2016; Arca Sedda et al. 2018; Kremer et al. 2018b; Kremer et al. 2019a; Zocchi et al. 2019; Antonini & Gieles 2020).”
• Merging black holes in young star clusters (2019, background): “In particular, the simulated SCs are assumed to be on a circular orbit around the center of the Milky Way with a semi-major axis of 8 kpc (Wang et al. 2016).”