TY - JOUR

T1 - Binary neutron star mergers

T2 - Dependence on the nuclear equation of state

AU - Hotokezaka, Kenta

AU - Kyutoku, Koutarou

AU - Okawa, Hirotada

AU - Shibata, Masaru

AU - Kiuchi, Kenta

PY - 2011/6/1

Y1 - 2011/6/1

N2 - We perform a numerical-relativity simulation for the merger of binary neutron stars with 6 nuclear-theory-based equations of states (EOSs) described by piecewise polytropes. Our purpose is to explore the dependence of the dynamical behavior of the binary neutron star merger and resulting gravitational waveforms on the EOS of the supernuclear-density matter. The numerical results show that the merger process and the first outcome are classified into three types: (i) a black hole is promptly formed, (ii) a short-lived hypermassive neutron star (HMNS) is formed, (iii) a long-lived HMNS is formed. The type of the merger depends strongly on the EOS and on the total mass of the binaries. For the EOS with which the maximum mass is larger than 2M, the lifetime of the HMNS is longer than 10ms for a total mass m0=2.7M. A recent radio observation suggests that the maximum mass of spherical neutron stars is M max 1.97±0.04M in one σ level. This fact and our results support the possible existence of a HMNS soon after the onset of the merger for a typical binary neutron star with m0=2.7M. We also show that the torus mass surrounding the remnant black hole is correlated with the type of the merger process; the torus mass could be large, 0.1M, in the case that a long-lived HMNS is formed. We also show that gravitational waves carry information of the merger process, the remnant, and the torus mass surrounding a black hole.

AB - We perform a numerical-relativity simulation for the merger of binary neutron stars with 6 nuclear-theory-based equations of states (EOSs) described by piecewise polytropes. Our purpose is to explore the dependence of the dynamical behavior of the binary neutron star merger and resulting gravitational waveforms on the EOS of the supernuclear-density matter. The numerical results show that the merger process and the first outcome are classified into three types: (i) a black hole is promptly formed, (ii) a short-lived hypermassive neutron star (HMNS) is formed, (iii) a long-lived HMNS is formed. The type of the merger depends strongly on the EOS and on the total mass of the binaries. For the EOS with which the maximum mass is larger than 2M, the lifetime of the HMNS is longer than 10ms for a total mass m0=2.7M. A recent radio observation suggests that the maximum mass of spherical neutron stars is M max 1.97±0.04M in one σ level. This fact and our results support the possible existence of a HMNS soon after the onset of the merger for a typical binary neutron star with m0=2.7M. We also show that the torus mass surrounding the remnant black hole is correlated with the type of the merger process; the torus mass could be large, 0.1M, in the case that a long-lived HMNS is formed. We also show that gravitational waves carry information of the merger process, the remnant, and the torus mass surrounding a black hole.

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U2 - 10.1103/PhysRevD.83.124008

DO - 10.1103/PhysRevD.83.124008

M3 - Article

AN - SCOPUS:79960750105

SN - 1550-7998

VL - 83

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

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

IS - 12

M1 - 124008

ER -