New code for quasiequilibrium initial data of binary neutron stars: Corotating, irrotational, and slowly spinning systems

Tsokaros, Antonios; Uryū, Kōji; Rezzolla, Luciano

doi:10.1103/physrevd.91.104030

Cited by 69 publications

(128 citation statements)

References 135 publications

(258 reference statements)

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“…Tsatsin and Marronetti [23] presented initial data and evolutions for nonspinning, spin-aligned, and antialigned data sets. Tsokaros et al [24] presented initial data and quasiequilibrium sequences of spin-aligned and antialigned binaries with a nuclear equation of state.…”

Section: Introductionmentioning

confidence: 99%

Binary neutron stars with arbitrary spins in numerical relativity

et al. 2015

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We present a code to construct initial data for binary neutron star systems in which the stars are rotating. Our code, based on a formalism developed by Tichy, allows for arbitrary rotation axes of the neutron stars and is able to achieve rotation rates near rotational breakup. We compute the neutron star angular momentum through quasilocal angular momentum integrals. When constructing irrotational binary neutron stars, we find a very small residual dimensionless spin of ∼2 × 10 −4 . Evolutions of rotating neutron star binaries show that the magnitude of the stars' angular momentum is conserved, and that the spin and orbit precession of the stars is well described by post-Newtonian approximation. We demonstrate that orbital eccentricity of the binary neutron stars can be controlled to ∼0.1%. The neutron stars show quasinormal mode oscillations at an amplitude which increases with the rotation rate of the stars.

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Section: Introductionmentioning

confidence: 99%

Binary neutron stars with arbitrary spins in numerical relativity

et al. 2015

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“…[23]. This method has now also been implemented by other groups [18,20]. There has also been some work on obtaining somewhat high mass ratios (up to q ¼ 1.5 [34,35]) and high compactnesses (up to C ≃ 0.26 [36]), but neither of these are close to the maximum mass ratios (at least ∼2; possibly up to ∼3 for a large maximum neutron star mass) and compactnesses (up to ∼0.3) that are (at least in principle) possible.…”

Section: Introductionmentioning

confidence: 96%

“…The highest compactness achieved for a neutron star in a relativistic binary is C ≃ 0.26 for a neutron star-black hole system [92], C ≃ 0.25 for corotating binary neutron stars [93], C ≃ 0.26 for irrotational binary neutron stars [36], and C ≃ 0.22 for binary neutron stars with relatively low spins [18].…”

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confidence: 99%

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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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“…The numerical methods used here are those implemented in the COCAL and ILLINOIS GRMHD codes, and have been described in great detail in our previous works [47][48][49][50][51][52][53][54][55][56][57], so we only summarize the most important features here.…”

Section: Methods and Physical Parametersmentioning

confidence: 99%

Gravitational wave content and stability of uniformly, rotating, triaxial neutron stars in general relativity

et al. 2017

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Targets for ground-based gravitational wave interferometers include continuous, quasiperiodic sources of gravitational radiation, such as isolated, spinning neutron stars. In this work we perform evolution simulations of uniformly rotating, triaxially deformed stars, the compressible analogues in general relativity of incompressible, Newtonian Jacobi ellipsoids. We investigate their stability and gravitational wave emission. We employ five models, both normal and supramassive, and track their evolution with different grid setups and resolutions, as well as with two different evolution codes. We find that all models are dynamically stable and produce a strain that is approximately one-tenth the average value of a merging binary system. We track their secular evolution and find that all our stars evolve towards axisymmetry, maintaining their uniform rotation, kinetic energy, and angular momentum profiles while losing their triaxiality.

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New code for quasiequilibrium initial data of binary neutron stars: Corotating, irrotational, and slowly spinning systems

Cited by 69 publications

References 135 publications

Binary neutron stars with arbitrary spins in numerical relativity

Binary neutron stars with arbitrary spins in numerical relativity

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

Gravitational wave content and stability of uniformly, rotating, triaxial neutron stars in general relativity

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