Equilibrium sequences of synchronized and irrotational binary systems composed of different mass stars in Newtonian gravity

Taniguchi, Keisuke; Gourgoulhon, Éric

doi:10.1103/physrevd.65.044027

Cited by 32 publications

(42 citation statements)

References 41 publications

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“…We have developed a numerical code for computing quasiequilibrium sequences of binary neutron stars through the series of works [24,25,34,35]. In the present article, we have presented the results of relativistic computations of both synchronized and irrotational rotation states, for polytropic equations of state with several adiabatic indices.…”

Section: Discussionmentioning

confidence: 99%

“…[25]. Consequently we presents here tests only regarding (i) the global numerical error measured by the virial theorem, (ii) the numerical error in the first law of binary neutron star thermodynamics, (iii) the comparison with previous numerical solutions, and (iv) the convergence to post-Newtonian results at large separation.…”

Section: Code Testsmentioning

confidence: 99%

“…Various approaches to compute binary neutron star models in the hydrodynamical inspiral phase have been considered: (i) (semi-)analytical [19,20] and (ii) numerical [21,22,23,24,25] in Newtonian gravity, (iii) (semi-)analytical [26,27,28,29] and (iv) numerical [30] in the post-Newtonian approximation, and (v) numerical in the framework of general relativity [31,32,33,34,35,36,37,38,39,40]. Binary neutron stars gradually decrease their orbital separations as a result of the emission of gravitational radiation.…”

Section: Introductionmentioning

confidence: 99%

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Various features of quasiequilibrium sequences of binary neutron stars in general relativity

2003

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Quasiequilibrium sequences of binary neutron stars are numerically calculated in the framework of the Isenberg-Wilson-Mathews (IWM) approximation of general relativity. The results are presented for both rotation states of synchronized spins and irrotational motion, the latter being considered as the realistic one for binary neutron stars just prior to the merger. We assume a polytropic equation of state and compute several evolutionary sequences of binary systems composed of different-mass stars as well as identical-mass stars with adiabatic indices γ = 2.5, 2.25, 2, and 1.8. From our results, we propose as a conjecture that if the turning point of binding energy (and total angular momentum) locating the innermost stable circular orbit (ISCO) is found in Newtonian gravity for some value of the adiabatic index γ0, that of the ADM mass (and total angular momentum) should exist in the IWM approximation of general relativity for the same value of the adiabatic index.

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Section: Discussionmentioning

confidence: 99%

Section: Code Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Various features of quasiequilibrium sequences of binary neutron stars in general relativity

2003

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“…The present article belongs to the series of works [11], [12] (hereafter Paper I), [13] (hereafter Paper II), [14], devoted to the intermediate phase. This stage is interesting because we may get informations about equation of state of neutron stars through the ISCO [15].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, it is important from a numerical point of view since it provides initial data for the dynamical simulation in the merging phase [7,8]. Then numerous theoretical efforts are devoted in this phase including (semi-)analytic Newtonian [16,17] and post-Newtonian [18,19,20,21] approaches and numerical Newtonian [13,14,22,23,24], post-Newtonian [25], and general relativistic [11,12,26,27,28,29,30,31,32] ones. Among these studies, we concentrate on numerical computations in the general relativistic framework.…”

Section: Introductionmentioning

confidence: 99%

Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity. III. Identical and different mass stars withγ=2

2002

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We present the first computations of quasiequilibrium binary neutron stars with different mass components in general relativity, within the Isenberg-Wilson-Mathews approximation. We consider both cases of synchronized rotation and irrotational motion. It is found that for identical mass binary systems there is no turning point of the binding energy (ADM mass) before the end point of the sequence (mass shedding point) in the irrotational case, while there is one before the end point of the sequence (contact point) in the synchronized case. On the other hand, in the different mass case, the sequence ends by the tidal disruption of the less massive star (mass shedding point). It is then more difficult to find a turning point in the ADM mass. Furthermore, we find that the deformation of each star depends mainly on the orbital separation and the mass ratio and very weakly on its compactness. On the other side, the decrease of the central energy density depends on the compactness of the star and not on that of the companion.

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SHTools: Tools for Working with Spherical Harmonics

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2018

Geochem Geophys Geosyst

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Geophysical analyses are often performed in spherical geometry and require the use of spherical harmonic functions to express observables or physical quantities. When expanded to high degree, the accuracy and speed of the spherical harmonic transforms and reconstructions are of paramount importance. SHTools is a time and user‐tested open‐source archive of both Fortran 95 and Python routines for performing spherical harmonic analyses. The routines support all spherical‐harmonic normalization conventions used in the geosciences, including 4π‐normalized, Schmidt seminormalized, orthonormalized, and unnormalized harmonics, along with the option of employing the Condon‐Shortley phase factor of (−1)m. Data on the sphere can be sampled on a variety of grid formats, including equally spaced cylindrical grids and grids appropriate for integration by Gauss‐Legendre quadrature. The spherical‐harmonic transforms are proven to be fast and accurate for spherical harmonic degrees up to 2800. Several tools are provided for the geoscientist, including routines for performing localized spectral analyses and basic operations related to global gravity and magnetic fields. In the Python environment, operations are very simple to perform as a result of three class structures that encompass all operations on grids, spherical harmonic coefficients, and spatiospectral localization windows. SHTools is released under the unrestrictive BSD 3‐clause license.

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Equilibrium sequences of synchronized and irrotational binary systems composed of different mass stars in Newtonian gravity

Cited by 32 publications

References 41 publications

Various features of quasiequilibrium sequences of binary neutron stars in general relativity

Various features of quasiequilibrium sequences of binary neutron stars in general relativity

Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity. III. Identical and different mass stars withγ=2

SHTools: Tools for Working with Spherical Harmonics

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