In this study, we begin by revisiting the oscillatory behavior of radiative quantities-energy, angular momentum, and linear momentum-linked with initial eccentricities in binary black hole (BBH) mergers. By varying the mean anomaly $l_0$ across the parameter range $[0,2π]$ from a post-Newtonian perspective, we establish an envelope that encapsulates the oscillations of these radiative quantities. Our analysis reveals that while the oscillations are influenced by the specific initial condition $l_0$, the effect of eccentricity contributes to the formation of this envelope. Subsequently, we model dynamical quantities such as peak luminosity $L_{\text{peak}}$, remnant mass $M_{\text{rem}}$, spin $α_{\text{rem}}$, and recoil velocity $V_{\text{rem}}$ in circular orbits. Through polynomial modeling, we explore their relationships with mass ratios and correlations. Our results demonstrate the effectiveness of these polynomials in capturing the intricate relationships and correlations among these quantities in circular orbits. Furthermore, we synthesize and analyze dynamical quantities for both circular and eccentric orbits, revealing continuous variations within specific ranges corresponding to distinct mass ratios. These variations are influenced by continuous changes in initial eccentricity and the associated envelope, which can be extrapolated to encompass other mass ratios. By interpolating the maximum and minimum values of these dynamical quantities, we unveil considerably broad domains relative to circular orbits in both orbital and non-orbital BBH mergers. These domains provide robust constraints on the relationships between dynamical quantities, mass ratios, and their correlations. Finally, we discuss the extension of this eccentricity effect to spin alignment and spin precession configurations of BBHs.
The Universal Eccentricity Distribution for Dynamical Gravitational-Wave Merger Channels
Institute for Advanced Study(高等研究院);University of Cambridge(剑桥大学);Gonville & Caius College(贡维尔与凯斯学院);Princeton University(普林斯顿大学);Cardiff University(卡迪夫大学);Niels Bohr International Academy, The Niels Bohr Institute(尼尔斯·玻尔国际学院,尼尔斯·玻尔研究所)
The origin of black hole mergers discovered by the LIGO and Virgo gravitational-wave observatories is currently unknown. GW190521 is the heaviest black hole merger detected so far. Its observed high mass and possible spin-induced orbital precession could arise from the binary having formed following a close encounter. An observational signature of close encounters is eccentric binary orbit; however, this feature is currently difficult to identify due to the lack of suitable gravitational waveforms. No eccentric merger has been previously found. Here we report 611 numerical relativity simulatio…
Impact of eccentricity on the population properties of neutron star - black hole mergers
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理研究所(爱因斯坦研究所));Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid(马德里自治大学理论物理研究所);School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham(伯明翰大学物理与天文学学院及引力波天文研究所)
The inspiral-merger-ringdown (IMR) consistency test checks the consistency of the final mass and final spin of a binary black hole merger remnant, independently inferred via the inspiral and merger-ringdown parts of the waveform. As binaries are expected to be nearly circularized when entering the frequency band of ground-based detectors, tests of general relativity (GR) currently employ quasicircular waveforms. We quantify the effect of residual orbital eccentricity on the IMR consistency test. We find that eccentricity causes a significant systematic bias in the inferred final mass and spin …
Kozai-Lidov (KL) oscillations can accelerate compact object mergers via gravitational wave (GW) radiation by driving the inner binaries of hierarchical triples to high eccentricities. We perform direct three-body integrations of high mass ratio compact object triple systems using Fewbody including post-Newtonian terms. We find that the inner binary undergoes rapid eccentricity oscillations (REOs) on the timescale of the outer orbital period which drive it to higher eccentricities than secular theory would otherwise predict, resulting in substantially reduced merger times. For a uniform distrib…
A universal framework to identify eccentric binary mergers: GW200105 case study
Princeton University(普林斯顿大学);Monash University(蒙纳士大学);OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery(引力波发现ARC卓越中心);Cardiff University(卡迪夫大学);University of Portsmouth(朴茨茅斯大学);Max Planck Institute for Astrophysics(马克斯·普朗克天体物理学研究所)
Mechanisms have been proposed to enhance the merger rate of stellar mass black hole binaries, such as the Von Zeipel-Lidov-Kozai mechanism (vZLK). However, high inclinations are required in order to greatly excite the eccentricity and to reduce the merger time through vZLK. Here, we propose a novel pathway through which compact binaries could merge due to eccentricity increase in general, including in a near coplanar configuration. Specifically, a compact binary migrating in an AGN disk could be captured in an evection resonance, when the precession rate of the binary equals their orbital peri…
We study the dynamical signatures of black hole (BH) and neutron star (NS) binary mergers via Lidov-Kozai oscillations induced by tertiary companions in hierarchical triple systems. For each type of binaries (BH-BH and BH-NS), we explore a wide range of binary/triple parameters that lead to binary mergers, and determine the distributions of eccentricity ($e_\mathrm{m}$) and spin-orbit misalignment angle ($θ_\rm {sl}^\rm f$) when the binary enters the LIGO/VIRGO band. We use the double-averaged (over both orbits) and single-averaged (over the inner orbit) secular equations, as well as N-body in…
Merger remnant and eccentricity dynamics surrogates for eccentric nonspinning black hole binaries
University of Massachusetts, Dartmouth(麻省大学达特茅斯分校);Max Planck Institute for Gravitational Physics(Albert Einstein Institute)(马克斯·普朗克引力物理研究所(爱因斯坦研究所));Cornell University(康奈尔大学);University of California Santa Barbara(加州大学圣塔芭芭拉分校);California State University Fullerton(加州州立大学富勒顿分校);Northwestern University(西北大学)
Eccentricity in Disguise? Insights from GW231123 and Numerically Simulated Binary Black Hole Merger Signals
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理研究所(爱因斯坦研究所));Institute for Gravitation & the Cosmos, Department of Physics, Penn State University(宾夕法尼亚州立大学引力与宇宙学研究所物理学系);Indian Institute of Technology, Bombay(印度理工学院孟买分校);Gran Sasso Science Institute (GSSI)(格兰萨索科学研究所);INFN, Laboratori Nazionali del Gran Sasso(意大利国家核物理研究所格兰萨索国家实验室);School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham(伯明翰大学物理与天文学院及引力波天文学研究所)
Orbital eccentricity in a neutron star - black hole merger
University of Birmingham(伯明翰大学);Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid(马德里自治大学理论物理研究所(UAM/CSIC));Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理学研究所(爱因斯坦研究所))
With better statistics and precision, eccentricity could prove to be a useful tool for understanding the origin and environment of binary black holes. Hierarchical triples in particular, which might be abundant in globular clusters and galactic nuclei, could generate observably large eccentricity at LIGO and future gravitational wave detectors. Measuring the eccentricity distribution accurately could help us probe the background and the formation of the mergers. In this paper we continue our previous investigation and improve our semi-analytical description of the eccentricity distribution of …
Black-hole - neutron-star mergers: new numerical-relativity simulations and multipolar effective-one-body model with spin precession and eccentricity
Universitat de les Illes Balears(巴利阿里群岛大学);Friedrich-Schiller-Universität Jena(耶拿弗里德里希·席勒大学);The Pennsylvania State University(宾夕法尼亚州立大学);University of California, Berkeley(加州大学伯克利分校);Università di Bologna(博洛尼亚大学)
Evidence for orbital eccentricity supports a hierarchical origin for GW231123
School of Physics and Technology, Wuhan University(武汉大学物理科学与技术学院);School of Physics and Astronomy, Beijing Normal University(北京师范大学物理与天文学院);Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理研究所(爱因斯坦研究所));Zhejiang Key Laboratory of Extreme Universe, Ningbo University(宁波大学极端宇宙浙江省重点实验室);Institute of Fundamental Physics and Quantum Technology, Ningbo University(宁波大学基础物理与量子技术研究院)
We study the spin and eccentricity evolution of black-hole (BH) binaries that are perturbed by tertiary masses and experience the Lidov-Kozai (LK) excitation. We focus on three aspects. Firstly, we study the spin-orbit alignment of the inner binary following the approach outlined by Antonini et al. [MNRAS 480, L58 (2018)] and Liu and Lai [ApJ 863, 68 (2018)], yet allowing the spins to have random initial orientations. We confirm the existence of a dynamical attractor that drives the spin-orbit angle at the end of the LK evolution to a value given by the initial angle between the spin and the o…
The radiation of linear momentum imparts a recoil (or "kick") to the center of mass of a merging black hole binary system. Recent numerical relativity calculations have shown that eccentricity can lead to an approximate 25% increase in recoil velocities for equal-mass, spinning binaries with spins lying in the orbital plane ("superkick" configurations) [U Sperhake et al. Phys. Rev. D 101 (2020) 024044 (arXiv:1910.01598)]. Here we investigate the impact of nonzero eccentricity on the kick magnitude and gravitational-wave emission of nonspinning, unequal-mass black hole binaries. We confirm that…
Inferring host environment properties and gravitational-wave decay time from the eccentricity measurement of dynamically captured binaries
Chennai Mathematical Institute(金奈数学研究所);Cardiff University(卡迪夫大学);Montclair State University(蒙克莱尔州立大学);Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理研究所(爱因斯坦研究所));Leibniz Universität Hannover(汉诺威莱布尼茨大学)
Stellar-mass black hole binaries (BHBs) near supermassive black holes (SMBH) in galactic nuclei undergo eccentricity oscillations due to gravitational perturbations from the SMBH. Previous works have shown that this channel can contribute to the overall BHB merger rate detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Interferometer. Significantly, the SMBH gravitational perturbations on the binary's orbit may produce eccentric BHBs which are expected to be visible using the upcoming Laser Interferometer Space Antenna (LISA) for a large fraction of their life…
The possible formation of stellar-mass binary black holes through dynamical interactions in dense stellar environments predicts the existence of binaries with non-negligible eccentricity in the frequency band of ground-based gravitational wave detectors; the detection of binary black hole mergers with measurable orbital eccentricity would validate the existence of this formation channel. Waveform templates currently used in the matched-filter gravitational-wave searches of LIGO-Virgo data neglect effects of eccentricity which is expected to reduce their efficiency to detect eccentric binary bl…
Spherical harmonic modes of gravitational waveforms for inspiraling compact binaries in eccentric orbits from post-Newtonian (PN) theory accurate to third post-Newtonian order, and those extracted from numerical relativity (NR) simulations for binary black holes (BBHs) are compared. We combine results from the two approaches (PN and NR) to construct time-domain hybrid waveforms that describe the complete evolution of BBH mergers through inspiral-merger-ringdown (IMR) stages. These hybrids are then used in constructing a fully analytical dominant mode ($\ell$=2, $|m|$=2) eccentric IMR model. A …
The Cost of Circularity: Quantifying Eccentricity-Induced Biases in Binary Black Hole Inference
University of Wisconsin–Milwaukee(威斯康星大学密尔沃基分校);The Pennsylvania State University(宾夕法尼亚州立大学);University of California, Berkeley(加州大学伯克利分校);University of Florida(佛罗里达大学)
We present new numerical-relativity simulations of eccentric merging black holes with initially antiparallel spins lying in the orbital plane (the so-called \emph{superkick} configuration). Binary eccentricity boosts the recoil of the merger remnant by up to $25\%$. The increase in the energy flux is much more modest, and therefore this kick enhancement is mainly due to asymmetry in the binary dynamics. Our findings might have important consequences for the retention of stellar-mass black holes in star clusters and supermassive black holes in galactic hosts.
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
基于 Dragon-II 的 19 个 N 体星团模拟,研究致密双星并合的质量、偏心率、并合率及不稳定对超新星率,揭示原初与动力学并合的差异,并给出多信使探测前景。
We develop a method to compute low-eccentricity initial data of binary neutron stars required to perform realistic simulations in numerical relativity. The orbital eccentricity is controlled by adjusting the orbital angular velocity of a binary and incorporating an approaching relative velocity of the neutron stars. These modifications improve the solution primarily through the hydrostatic equilibrium equation for the binary initial data. The orbital angular velocity and approaching velocity of initial data are updated iteratively by performing time evolutions over ~3 orbits. We find that the …
Information about the last stages of a binary neutron star inspiral and the final merger can be extracted from quasi-equilibrium configurations and dynamical evolutions. In this article, we construct quasi-equilibrium configurations for different spins, eccentricities, mass ratios, compactnesses, and equations of state. For this purpose we employ the SGRID code, which allows us to construct such data in previously inaccessible regions of the parameter space. In particular, we consider spinning neutron stars in isolation and in binary systems; we incorporate new methods to produce highly eccent…
Black-hole (BH) binary mergers driven by gravitational perturbations of tertiary companions constitute an important class of dynamical formation channels for compact binaries detected by LIGO/VIRGO. Recent works have examined numerically the combined orbital and spin dynamics of BH binaries that undergo large Lidov-Kozai (LK) eccentricity oscillations induced by a highly inclined companion and merge via gravitational wave radiation. However, the extreme eccentricity variations make such systems difficult to characterize analytically. In this paper, we develop an analytical formalism for unders…
The origin and formation of stellar-mass binary black holes remains an open question that can be addressed by precise measurements of the binary and orbital parameters from their gravitational-wave signal. Such binaries are expected to circularize due to the emission of gravitational waves as they approach merger. However, depending on their formation channel, some binaries could have a non-negligible eccentricity when entering the frequency band of current gravitational-wave detectors. In order to measure eccentricity in an observed gravitational-wave signal, accurate waveform models that des…
Black hole (BH) mergers driven by gravitational perturbations of external companions constitute an important class of formation channels for merging BH binaries detected by LIGO. We have studied the orbital and spin evolution of binary BHs in triple systems, where the tertiary companion excites large eccentricity in the inner binary through Lidov-Kozai oscillations, causing the binary to merge via gravitational radiation. Using the single-orbital-averaged and double-orbital-averaged secular dynamics equations of triples, we determine the merger window (the range of companion inclinations that …
We study the general relativitic (GR) effects induced by a spinning supermassive black hole on the orbital and spin evolution of a merging black hole binary (BHB) in a hierarchical triple system. A sufficiently inclined outer orbit can excite Lidov-Kozai eccentricity oscillations in the BHB and induce its merger. These GR effects generate extra precessions on the BHB orbits and spins, significantly increasing the inclination window for mergers and producing a wide range of spin orientations when the BHB enters LIGO band. This "GR-enhanced" channel may play an important role in BHB mergers.
The environment surrounding supermassive black holes (SMBHs) in galactic nuclei (GNs) is expected to harbour stellar-mass binary black hole (BBH) populations. These binaries were suggested to form a hierarchical triple system with the SMBH, and gravitational perturbations from the SMBH can enhance the mergers of BBHs through Lidov-Kozai (LK) oscillations. Previous studies determined the expected binary parameter distribution for this merger channel in single GNs. Here we account for the different spatial distribution and mass distribution models of BBHs around SMBHs and perform direct high-pre…
The gravitational-wave (GW) detection of GW190521 has provided new insights on the mass distribution of black holes and new constraints for astrophysical formation channels. With independent claims of GW190521 having significant pre-merger eccentricity, we investigate what this implies for GW190521-like binaries that form dynamically. The Laser Interferometer Space Antenna (LISA) will also be sensitive to GW190521-like binaries if they are circular from an isolated formation channel. We show, however, that GW190521-like binaries that form dynamically may skip the LISA band entirely. To this en…
Orbital eccentricity is a key signature of dynamical binary black hole formation. The gravitational waves from a coalescing binary contain information about its orbital eccentricity, which may be measured if the binary retains sufficient eccentricity near merger. Dedicated waveforms are required to measure eccentricity. Several models have been put forward, and show good agreement with numerical relativity at the level of a few percent or better. However, there are multiple ways to define eccentricity for inspiralling systems, and different models internally use different definitions of eccent…
Numerical simulations of low-mass black hole-neutron star mergers with moderate eccentricities
Institut für Physik und Astronomie, Universität Potsdam(波茨坦大学物理与天文学研究所);Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理学研究所(爱因斯坦研究所))
Using a post-Newtonian diagnostic tool developed by Mora and Will, we examine numerically generated quasiequilibrium initial data sets that have been used in recently successful numerical evolutions of binary black holes through plunge, merger and ringdown. We show that a small but significant orbital eccentricity is required to match post-Newtonian and quasiequilibrium calculations. If this proves to be a real eccentricity, it could affect the fine details of the subsequent numerical evolutions and the predicted gravitational waveforms.
The LIGO/Virgo collaborations recently announced the detection of a likely binary neutron star merger, GW190425. The total mass of GW190425 is significantly larger than the masses of Galactic double neutron stars known through radio astronomy. This suggests that GW190425 formed differently from Galactic double neutron stars. We hypothesize that GW190425 formed via unstable "case BB" mass transfer. According to this hypothesis, the progenitor of GW190425 was a binary consisting of a neutron star and a ${\sim} 4-5 {M_\odot}$ helium star, which underwent a common-envelope process. Following the s…
Biased parameter inference of eccentric, spin-precessing binary black holes
Cardiff University(卡迪夫大学);Indian Institute of Technology Madras(马德拉斯印度理工学院);Penn State University(宾夕法尼亚州立大学);Tata Institute of Fundamental Research(塔塔基础研究所)
Black hole (BH) binary mergers formed through dynamical interactions in dense star clusters are believed to be one of the main sources of gravitational waves for Advanced LIGO and Virgo. Here we present a fast numerical method for simulating the evolution of star clusters with BHs, including a model for the dynamical formation and merger of BH binaries. Our method is based on Hénon's principle of balanced evolution, according to which the flow of energy within a cluster must be balanced by the energy production inside its core. Because the heat production in the core is powered by the BHs, one…
We apply the theory of nonlinear resonance capture to the problem of a black hole binary (BHB) orbiting a supermassive black hole (SMBH) while embedded in the accretion disk of an active galactic nucleus (AGN). If successful, resonance capture can trigger dramatic growth in the BHB eccentricity, with important consequences for the BHB merger timescale, as well as for the gravitational wave (GW) signature of such an eccentric merger. This resonance capture may occur when the orbital period around the SMBH (the "outer binary") and the apsidal precession of the BHB (the "inner binary") are in a 1…
The problem of gravitational wave parameter estimation and source localization is crucial in gravitational wave astronomy. Gravitational waves emitted by compact binary coalescences in the sensitivity band of second-generation ground-based detectors could have non-negligible eccentricities. Thus it is an interesting topic to study how the eccentricity of a binary source affects and improves the accuracy of its localization (and the signal-to-noise ratio). In this work we continue to investigate this effect with the enhanced postcircular waveform model. Using the Fisher information matrix metho…
Quasi-Normal Mode Ringing of Binary Black Hole Mergers in Scalar-Gauss-Bonnet Gravity
Peking University(北京大学);Kavli Institute for Astronomy and Astrophysics, Peking University(北京大学科维理天文与天体物理研究所);Eberhard Karls University of Tübingen(蒂宾根大学);INRNE - Bulgarian Academy of Sciences(保加利亚科学院核研究与核能研究所);Sofia University “St. Kliment Ohridski”(索菲亚大学);Institute of Mathematics and Informatics, Bulgarian Academy of Sciences(保加利亚科学院数学与信息学研究所);National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台)