### Abstract

We perform new long-term (15-16 orbits) simulations of coalescing binary neutron stars in numerical relativity using an updated Einstein equation solver, employing low-eccentricity initial data, and modeling the neutron stars by a piecewise polytropic equation of state. A convergence study shows that our new results converge more rapidly than the third order, and using the determined convergence order, we construct an extrapolated waveform for which the estimated total phase error should be less than one radian. We then compare the extrapolated waveforms with those calculated by the latest effective-one-body (EOB) formalism in which the so-called tidal deformability, higher post-Newtonian corrections, and gravitational self-force effects are taken into account. We show that for a binary of compact neutron stars with their radius 11.1 km, the waveform by the EOB formalism agrees quite well with the numerical waveform so that the total phase error is smaller than one radian for the total phase of ∼200 radian up to the merger. By contrast, for a binary of less compact neutron stars with their radius 13.6 km, the EOB and numerical waveforms disagree with each other in the last few wave cycles, resulting in the total phase error of approximately three radian.

Original language | English |
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Article number | 064060 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 91 |

Issue number | 6 |

DOIs | |

Publication status | Published - 2015 Mar 26 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*91*(6), [064060]. https://doi.org/10.1103/PhysRevD.91.064060

**Exploring tidal effects of coalescing binary neutron stars in numerical relativity. II. Long-term simulations.** / Hotokezaka, Kenta; Kyutoku, Koutarou; Okawa, Hirotada; Shibata, Masaru.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 91, no. 6, 064060. https://doi.org/10.1103/PhysRevD.91.064060

}

TY - JOUR

T1 - Exploring tidal effects of coalescing binary neutron stars in numerical relativity. II. Long-term simulations

AU - Hotokezaka, Kenta

AU - Kyutoku, Koutarou

AU - Okawa, Hirotada

AU - Shibata, Masaru

PY - 2015/3/26

Y1 - 2015/3/26

N2 - We perform new long-term (15-16 orbits) simulations of coalescing binary neutron stars in numerical relativity using an updated Einstein equation solver, employing low-eccentricity initial data, and modeling the neutron stars by a piecewise polytropic equation of state. A convergence study shows that our new results converge more rapidly than the third order, and using the determined convergence order, we construct an extrapolated waveform for which the estimated total phase error should be less than one radian. We then compare the extrapolated waveforms with those calculated by the latest effective-one-body (EOB) formalism in which the so-called tidal deformability, higher post-Newtonian corrections, and gravitational self-force effects are taken into account. We show that for a binary of compact neutron stars with their radius 11.1 km, the waveform by the EOB formalism agrees quite well with the numerical waveform so that the total phase error is smaller than one radian for the total phase of ∼200 radian up to the merger. By contrast, for a binary of less compact neutron stars with their radius 13.6 km, the EOB and numerical waveforms disagree with each other in the last few wave cycles, resulting in the total phase error of approximately three radian.

AB - We perform new long-term (15-16 orbits) simulations of coalescing binary neutron stars in numerical relativity using an updated Einstein equation solver, employing low-eccentricity initial data, and modeling the neutron stars by a piecewise polytropic equation of state. A convergence study shows that our new results converge more rapidly than the third order, and using the determined convergence order, we construct an extrapolated waveform for which the estimated total phase error should be less than one radian. We then compare the extrapolated waveforms with those calculated by the latest effective-one-body (EOB) formalism in which the so-called tidal deformability, higher post-Newtonian corrections, and gravitational self-force effects are taken into account. We show that for a binary of compact neutron stars with their radius 11.1 km, the waveform by the EOB formalism agrees quite well with the numerical waveform so that the total phase error is smaller than one radian for the total phase of ∼200 radian up to the merger. By contrast, for a binary of less compact neutron stars with their radius 13.6 km, the EOB and numerical waveforms disagree with each other in the last few wave cycles, resulting in the total phase error of approximately three radian.

UR - http://www.scopus.com/inward/record.url?scp=84927670499&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84927670499&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.91.064060

DO - 10.1103/PhysRevD.91.064060

M3 - Article

AN - SCOPUS:84927670499

VL - 91

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 6

M1 - 064060

ER -