Including realistic tidal deformations in binary black-hole initial data

Chu, Tony

doi:10.1103/physrevd.89.064062

Cited by 12 publications

(21 citation statements)

References 74 publications

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“…The assumption of conformal flatness is thus thought to be responsible for at least some of the initial spurious radiation observed at the beginning of all numerical relativity simulations of compact binaries. (One finds reductions in some components of the initial spurious radiation when one drops the assumption of conformal flatness in the binary black hole case, e.g., [58][59][60][61][62].) The waveless approach [63,64] involves a (constraint-solved) construction of binary neutron star data that does not assume spatial conformal flatness, with some unpublished evolutions [65], but in general this aspect has not been studied nearly as well for binary neutron stars as for binary black holes.…”

Section: A Extended Conformal Thin-sandwich Formulationmentioning

confidence: 99%

Initial data for binary neutron stars with adjustable eccentricity

et al. 2014

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Binary neutron stars in circular orbits can be modeled as helically symmetric, i.e., stationary in a rotating frame. This symmetry gives rise to a first integral of the Euler equation, often employed for constructing equilibrium solutions via iteration. For eccentric orbits, however, the lack of helical symmetry has prevented the use of this method, and the numerical relativity community has often resorted to constructing initial data by superimposing boosted spherical stars without solving the Euler equation. The spuriously excited neutron star oscillations seen in evolutions of such data arise because such configurations lack the appropriate tidal deformations and are stationary in a linearly comoving-rather than rotating-frame. We consider eccentric configurations at apoapsis that are instantaneously stationary in a rotating frame. We extend the notion of helical symmetry to eccentric orbits, by approximating the elliptical orbit of each companion as instantaneously circular, using the ellipse's inscribed circle. The two inscribed helical symmetry vectors give rise to approximate instantaneous first integrals of the Euler equation throughout each companion. We use these integrals as the basis of a self-consistent iteration of the Einstein constraints to construct conformal thin-sandwich initial data for eccentric binaries. We find that the spurious stellar oscillations are reduced by at least an order of magnitude, compared with those found in evolutions of superposed initial data. The tidally induced oscillations, however, are physical and qualitatively similar to earlier evolutions. Finally, we show how to incorporate radial velocity due to radiation reaction in our inscribed helical symmetry vectors, which would allow one to obtain truly non-eccentric initial data when our eccentricity parameter e is set to zero.

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Section: A Extended Conformal Thin-sandwich Formulationmentioning

confidence: 99%

Initial data for binary neutron stars with adjustable eccentricity

et al. 2014

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“…However, since the expected lowest-order Newtonian tidal deformations are not present in conformally flat data in the binary black hole case-see, e.g., Ref. [146]-it does not seem to make any sense to include them here.) Here the expressions for the orbit in the Appendix of Ref.…”

Section: The Approximate Symmetry Vectormentioning

confidence: 99%

Binary neutron stars with generic spin, eccentricity, mass ratio, and compactness: Quasi-equilibrium sequences and first evolutions

Dietrich¹,

Moldenhauer²,

et al. 2015

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Information about the last stages of a binary neutron star inspiral and the final merger can be extracted from quasiequilibrium configurations and dynamical evolutions. In this article, we construct quasiequilibrium 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 eccentric and eccentricity-reduced data; we present the possibility of computing data for significantly unequal-mass binaries with mass ratios q ≃ 2; and we create equal-mass binaries with individual compactness up to C ≃ 0.23. As a proof of principle, we explore the dynamical evolution of three new configurations. First, we simulate a q ¼ 2.06 mass ratio which is the highest mass ratio for a binary neutron star evolved in numerical relativity to date. We find that mass transfer from the companion star sets in a few revolutions before merger and a rest mass of ∼10 −2 M ⊙ is transferred between the two stars. This amount of mass accretion corresponds to ∼10 51 ergs of accretion energy. This configuration also ejects a large amount of material during merger (∼7.6 × 10 −2 M ⊙ ), imparting a substantial kick to the remnant neutron star. Second, we simulate the first merger of a precessing binary neutron star. We present the dominant modes of the gravitational waves for the precessing simulation, where a clear imprint of the precession is visible in the (2,1) mode. Finally, we quantify the effect of an eccentricity-reduction procedure on the gravitational waveform. The procedure improves the waveform quality and should be employed in future precision studies. However, one also needs to reduce other errors in the waveforms, notably truncation errors, in order for the improvement due to eccentricity reduction to be effective.

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“…18) in the limit r → ∞.From now on we restrict to the case n = 2. We write M + = M 1 , M − = M 2 and set r + = r 1 = (0, 0, Z), r − = r 2 = (0, 0, −Z)for some fixed Z ≥ 0 and M + , M − ≥ 0.…”

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confidence: 99%

Numerical construction of initial data sets of binary black hole type using a parabolic-hyperbolic formulation of the vacuum constraint equations

Beyer

Escobar

Frauendiener

et al. 2019

Class. Quantum Grav.

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In this paper we investigate the parabolic-hyperbolic formulation of the vacuum constraint equations introduced by Rácz with a view to constructing multiple black hole initial data sets without spin. In order to respect the natural properties of this configuration, we foliate the spatial domain with 2-spheres. It is then a consequence of these equations that they must be solved as an initial value problem evolving outwards towards spacelike infinity. Choosing the free data and the "strong field boundary conditions" for these equations in a way which mimics asymptotically flat and asymptotically spherical binary black hole initial data sets, our focus in this paper is on the analysis of the asymptotics of the solutions. In agreement with our earlier results, our combination of analytical and numerical tools reveals that these solutions are in general not asymptotically flat, but have a cone geometry instead. In order to remedy this and approximate asymptotically Euclidean data sets, we then propose and test an iterative numerical scheme. *

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Including realistic tidal deformations in binary black-hole initial data

Cited by 12 publications

References 74 publications

Initial data for binary neutron stars with adjustable eccentricity

Initial data for binary neutron stars with adjustable eccentricity

Binary neutron stars with generic spin, eccentricity, mass ratio, and compactness: Quasi-equilibrium sequences and first evolutions

Numerical construction of initial data sets of binary black hole type using a parabolic-hyperbolic formulation of the vacuum constraint equations

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