Compact binary mergers forming in star clusters may exhibit distinctive features that can be used to identify them among observed gra vitational-wa ve 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 < 33 per cent 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, ∼ 30 per cent 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 R ∼ 30(4 . 4)(1 . 2) 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 surv e ys 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.
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
Manuel Arca-sedda
Investigation
;
2024-01-01
Abstract
Compact binary mergers forming in star clusters may exhibit distinctive features that can be used to identify them among observed gra vitational-wa ve 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 < 33 per cent 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, ∼ 30 per cent 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 R ∼ 30(4 . 4)(1 . 2) 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 surv e ys 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
