The dragon-II simulations – III. Compact binary mergers in clusters with up to 1 million stars: mass, spin, eccentricity, merger rate, and pair instability supernovae rate
Jul 10, 202322 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 528 (2024) 3, 5140-5159
- Published: Feb 7, 2024
e-Print:
- 2307.04807 [astro-ph.HE]
View in:
Citations per year
Abstract: (Oxford University Press)
Compact binary mergers forming in star clusters may exhibit distinctive features that can be used to identify them among observed gravitational-wave sources. Such features likely depend on the host cluster structure and the physics of massive star evolution. Here, we dissect the population of compact binary mergers in the dragon-II simulation data base, a suite of 19 direct N-body models representing dense star clusters with up to 10^6 stars and || of stars in primordial binaries. We find a substantial population of black hole binary (BBH) mergers, some of them involving an intermediate-mass BH (IMBH), and a handful mergers involving a stellar BH and either a neutron star (NS) or a white dwarf (WD). Primordial binary mergers, || of the whole population, dominate ejected mergers. Dynamical mergers, instead, dominate the population of in-cluster mergers and are systematically heavier than primordial ones. Around 20 per cent of dragon-II mergers are eccentric in the Laser Interferometer Space Antenna (LISA) band and 5 per cent in the LIGO band. We infer a mean cosmic merger rate of || yr^−1 Gpc^−3 for BBHs, NS–BH, and WD–BH binary mergers, respectively, and discuss the prospects for multimessenger detection of WD–BH binaries with LISA. We model the rate of pair-instability supernovae (PISNe) in star clusters and find that surveys with a limiting magnitude m_bol = 25 can detect ∼1–15 yr^−1 PISNe. Comparing these estimates with future observations could help to pin down the impact of massive star evolution on the mass spectrum of compact stellar objects in star clusters.Note:
- 22 pages, 14 figures, 3 tables. Comments welcome. Submitted to MNRAS
- methods: numerical
- stars: general
- stars: black holes
- galaxies: star clusters: general
References(354)
Figures(20)