Eccentric binary black-hole mergers: The transition from inspiral to plunge in general relativity

Physical review D: Particles and fields (Impact Factor: 4.86). 11/2007; 78(6). DOI: 10.1103/PHYSREVD.78.064069
Source: arXiv


We study the transition from inspiral to plunge in general relativity by computing gravitational waveforms of non-spinning, equal-mass black-hole binaries. We consider three sequences of simulations, starting with a quasi-circular inspiral completing 1.5, 2.3 and 9.6 orbits, respectively, prior to coalescence of the holes. For each sequence, the binding energy of the system is kept constant and the orbital angular momentum is progressively reduced, producing orbits of increasing eccentricity and eventually a head-on collision. We analyze in detail the radiation of energy and angular momentum in gravitational waves, the contribution of different multipolar components and the final spin of the remnant. We find that the motion transitions from inspiral to plunge when the orbital angular momentum L=L_crit is about 0.8M^2. For L<L_crit the radiated energy drops very rapidly. Orbits with L of about L_crit produce our largest dimensionless Kerr parameter for the remnant, j=J/M^2=0.724. Generalizing a model recently proposed by Buonanno, Kidder and Lehner to eccentric binaries, we conjecture that (1) j=0.724 is the maximal Kerr parameter that can be obtained by any merger of non-spinning holes, and (2) no binary merger (even if the binary members are extremal Kerr black holes with spins aligned to the orbital angular momentum, and the inspiral is highly eccentric) can violate the cosmic censorship conjecture.

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Available from: José A. González, May 18, 2015
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    • "These results quickly transformed the field which was now able to effectively evolve the Einstein field equations for coalescing BH-BH binaries and other systems containing moving BHs, including merging BH-NS binaries. These breakthroughs had direct relevance to astrophysics, and enabled exciting new results on recoil velocities from BH-BH mergers (e.g, [11] [12] [13] [14] [15] [16] and references therein), post-Newtonian (PN) and numerical waveform comparisons and waveform template generation (e.g., [17] [18] [19] [20] [21] [22] [23] [24] [25] and references therein), comparisons between numerical waveforms [26] [27], determination of the spin of the remnant BH formed in BH-BH mergers (e.g, [28] [29] [30] [31] [32] [33] and references therein), and studies of eccentric BH-BH binaries [34] [35] [36] [37] [38] [39]. Meanwhile, general relativistic magneto-hydrodynamics (GRMHD) on fixed background spacetimes has been successful in multi-dimensional settings since the mid-1990s, focusing on BH accretion processes and relativistic jet production and evolution (see [40] for a review of the numerical formalism and [41] for a review of work on disk and jet models). "
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    ABSTRACT: We describe the Einstein Toolkit, a community-driven, freely accessible computational infrastructure intended for use in numerical relativity, relativistic astrophysics, and other applications. The Toolkit, developed by a collaboration involving researchers from multiple institutions around the world, combines a core set of components needed to simulate astrophysical objects such as black holes, compact objects, and collapsing stars, as well as a full suite of analysis tools. The Einstein Toolkit is currently based on the Cactus Framework for high-performance computing and the Carpet adaptive mesh refinement driver. It implements spacetime evolution via the BSSN evolution system and general-relativistic hydrodynamics in a finite-volume discretization. The toolkit is under continuous development and contains many new code components that have been publicly released for the first time and are described in this article. We discuss the motivation behind the release of the toolkit, the philosophy underlying its development, and the goals of the project. A summary of the implemented numerical techniques is included, as are results of numerical test covering a variety of sample astrophysical problems.
    Classical and Quantum Gravity 11/2011; 29(11). DOI:10.1088/0264-9381/29/11/115001 · 3.17 Impact Factor
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    • "Analogous variations have been observed in the mass of the merger remnant as well as in the final spin in [16]. However, these oscillatory features have not been observed by [14] [18], while the behaviour for low Θ looks very similar to [13]. In the following we will explore the origin of the above findings in more detail. "
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    ABSTRACT: We study zoom-whirl behaviour of equal mass, non-spinning black hole binaries in full general relativity. The magnitude of the linear momentum of the initial data is fixed to that of a quasi-circular orbit, and its direction is varied. We find a global maximum in radiated energy for a configuration which completes roughly one orbit. The radiated energy in this case exceeds the value of a quasi-circular binary with the same momentum by 15%. The direction parameter only requires minor tuning for the localization of the maximum. There is non-trivial dependence of the energy radiated on eccentricity (several local maxima and minima). Correlations with orbital dynamics shortly before merger are discussed. While being strongly gauge dependent, these findings are intuitive from a physical point of view and support basic ideas about the efficiency of gravitational radiation from a binary system.
    Classical and Quantum Gravity 04/2010; 27(8):084035. DOI:10.1088/0264-9381/27/8/084035 · 3.17 Impact Factor
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    • "As highlighted in [8] [13], in the evolutions we use, as the eccentricity is increased there is a transition from inspiral to plunge at around e ∼ 0.5. Actually without specifying the initial separation along with the orbital period/eccentricity as done in [8], the eccentricity by itself would not be a meaningful parameter. "
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    ABSTRACT: Owing to the difficulty of direct observation, mergers of intermediate-mass black hole binaries are relatively less understood compared to stellar-mass binaries; however, the gravitational waves from their last few orbits and ringdown fall in the band of ground-based detectors. Because the typical source is expected to circularize prior to entering LIGO or VIRGO's range, inspiral searches concentrate on circularized binaries. It is possible that events will be missed if there are sources with residual eccentricity. We study the variation of the signal to noise present in the dominant mode of the eccentric evolutions as a function of mass and eccentricity and also the relative contribution of the signal in the various spherical harmonic modes. The energy radiated in gravitational waves increases with eccentricity until the eccentricity becomes too high, leading to plunging trajectories, at which point the energy radiated decreases. This enhancement of the energy for initial eccentricities near the transition value translates into larger signal-to-noise ratios. Consequently despite the anticipated loss in the signal-to-noise ratio due to the use of quasi-circular detection templates, some eccentric signals potentially may be seen farther out than others.
    Classical and Quantum Gravity 10/2009; 26(20). DOI:10.1088/0264-9381/26/20/204008 · 3.17 Impact Factor
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