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Article Dans Une Revue Physical Review D Année : 2009

Nonconformally flat initial data for binary compact objects

Résumé

A new method is described for constructing initial data for a binary neutron-star system in quasiequilibrium circular orbit. Two formulations for nonconformally flat data, waveless and near-zone helically symmetric, are introduced; in each formulation, the Einstein-Euler system, written in 3+1 form on an asymptotically flat spacelike hypersurface, is exactly solved for all metric components, including the spatially nonconformally flat potentials, and for irrotational flow. A numerical method applicable to both formulations is explained with an emphasis on the imposition of a spatial gauge condition. Results are shown for solution sequences of irrotational binary neutron-stars with matter approximated by parametrized equations of state that use a few segments of polytropic equations of state. The binding energy and total angular momentum of solution sequences computed within the conformally flat---Isenberg-Wilson-Mathews---formulation are closer to those of the third post-Newtonian (3PN) two point particles up to the closest orbits, for the more compact stars, whereas sequences resulting from the waveless/near-zone helically symmetric formulations deviate from the 3PN curve even more for the sequences with larger compactness. We think it likely that this correction reflects an overestimation in the Isenberg-Wilson-Mathews formulation as well as in the 3PN formula, by ˜1 cycle in the gravitational-wave phase during the last several orbits. The work suggests that imposing spatial conformal flatness results in an underestimate of the quadrupole deformation of the components of binary neutron-star systems in the last few orbits prior to merger.

Dates et versions

hal-03742439 , version 1 (02-08-2022)

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Citer

Koji Uryu, François Limousin, John L. Friedman, Éric Gourgoulhon, Masaru Shibata. Nonconformally flat initial data for binary compact objects. Physical Review D, 2009, 80, pp.124004. ⟨10.1103/PhysRevD.80.124004⟩. ⟨hal-03742439⟩
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