文章基本信息

标题：The origin of spin in binary black holes
其他标题：Predicting the distributions of the main observables of Advanced LIGO
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作者：Simone S. Bavera ; Tassos Fragos ; Ying Qin 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2020
卷号：635
页码：1-18
DOI：10.1051/0004-6361/201936204
语种：English
出版社：EDP Sciences
摘要：Context.After years of scientific progress, the origin of stellar binary black holes is still a great mystery. Several formation channels for merging black holes have been proposed in the literature. As more merger detections are expected with future gravitational-wave observations, population synthesis studies can help to distinguish between them.Aims.We study the formation of coalescing binary black holes via the evolution of isolated field binaries that go through the common envelope phase in order to obtain the combined distributions of observables such as black-hole spins, masses and cosmological redshifts of mergers.Methods.To achieve this aim, we used a hybrid technique that combines the parametric binary population synthesis code COMPAS with detailed binary evolution simulations performed with the MESA code. We then convolved our binary evolution calculations with the redshift- and metallicity-dependent star-formation rate and the selection effects of gravitational-wave detectors to obtain predictions of observable properties.Results.By assuming efficient angular momentum transport, we are able to present a model that is capable of simultaneously predicting the following three main gravitational-wave observables: the effective inspiral spin parameterχeff, the chirp massMchirpand the cosmological redshift of mergerzmerger. We find an excellent agreement between our model and the ten events from the first two advanced detector observing runs. We make predictions for the third observing run O3 and for Advanced LIGO design sensitivity. We expect approximately 80% of events withχeff < 0.1, while the remaining 20% of events withχeff ≥ 0.1 are split into ∼10% withMchirp < 15 M⊙and ∼10% withMchirp ≥ 15 M⊙. Moreover, we find thatMchirpandχeffdistributions are very weakly dependent on the detector sensitivity.Conclusions.The favorable comparison of the existing LIGO/Virgo observations with our model predictions gives support to the idea that the majority, if not all of the observed mergers, originate from the evolution of isolated binaries. The first-born black hole has negligible spin because it lost its envelope after it expanded to become a giant star, while the spin of the second-born black hole is determined by the tidal spin up of its naked helium star progenitor by the first-born black hole companion after the binary finished the common-envelope phase.
关键词：enstars: black holesgravitational wavesbinaries closeblack hole physics