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Numerical analysis for merger of binary neutron stars in full general relativity

完全广义相对论中双中子星并合的数值分析

基本信息

批准号：
17540232
负责人：
SHIBATA Masaru
金额：
$ 2.18万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

Astrophysical systems of two neutron stars are referred to as binary neutron stars. Such binary of close orbits emits gravitational waves, resulting in decreasing the orbital separation to merger. According to statistical studies, the merger happens once a year in a distance of 50 Mpc around our Galaxy. In the last about 15 minutes just before the merger, gravitational waves of more than 10Hz is emitted. Such high frequency gravitational waves are among the most promising sources of gravitational wave detector such as LIGO. Predicting the gravitational waveforms is an issue in theoretical astrophysics.After merger of binary neutron stars, a black hole or a hypermassive neutron star (HMNS) is formed. If a black hole surrounded by massive, hot, and dense torus is formed, it may be a central engine of gamma-ray burst. Although this hypothesis has been proposed for about 20 years, no one knows if it is correct. It is one of the important issues in astrophysics to clarify whether this scena … More rio is correct or not.By these two motivations, we have performed numerical simulations in full general relativity for two years. We have reached the following conclusion. (1) A black hole is formed after merger of binary neutron stars if the total mass exceeds a critical mass. It depends on the equation of state of neutron stars ; for plausible stiff nuclear equations of state, the critical mass is 2.6-2.8 solar mass. (2) If the total mass is smaller than the critical mass, an HMNS of elliptical shape is formed. Because of its elliptic shape, the HMNS emits gravitational waves and dissipates angular momentum. As a result of the reduced centrifugal force, the HMNS collapses to a black hole in about 100 ms. (3) Accretion torus is formed around a black hole if the mass ratio of binary neutron stars is not unity. But even for the mass ratio 2/3, the torus mass is about 10% of the solar mass. (4) For the black hole formation, gravitational waves associated with the quasinormal mode ringing are emitted in the last moment.The amplitude is about 10^<-23> at a distance of 50 Mpc and the frequency is about 7 kHz. It is very difficult to detect such gravitational waves unless the merger happens around our Galaxy by chance. (5) In the case of HMNS formation, quasiperiodic gravitational waves are emitted due to rotation of elliptic HMNS. The effective amplitude is about 10^<-20> at a distance of 50 Mpc and the frequency is about 3 kHz. Such gravitational waves may be detected by the next-generation detectors. (6) After merger of unequal mass binaries, a black hole surrounded by a massive torus is formed. Such system is a candidate of the central engine of gamma-ray bursts. Less

由两颗中子星组成的天体物理系统称为中子双星。这种轨道接近的双星发射引力波，导致轨道分离减少合并。根据统计研究，合并每年发生一次，距离我们银河系50 Mpc。在合并前的最后15分钟，会发射出超过10赫兹的引力波。这种高频引力波是LIGO等引力波探测器最有希望的来源之一。中子星双星合并后会形成黑洞或超大质量中子星星（HMNS），预测引力波形是理论天体物理学中的一个重要问题。如果形成一个被巨大、炽热和致密的环面包围的黑洞，它可能是伽马射线爆发的中心引擎。虽然这个假设已经提出了大约20年，但没有人知道它是否正确。阐明这一景象是否是天体物理学的重要问题之一， ...更多信息基于这两个动机，我们已经在完全广义相对论中进行了两年的数值模拟。我们得出以下结论。(1)当中子星的总质量超过一个临界质量时，就会形成一个黑洞。它取决于中子星的状态方程;对于看似刚性的核状态方程，临界质量是2.6-2.8太阳质量。(2)如果总质量小于临界质量，则形成椭圆形状的HMNS。由于它的椭圆形状，HMNS发射引力波并耗散角动量。由于离心力的减小，HMNS在100 ms左右坍缩成黑洞。（3）当中子星质量比不为1时，黑洞周围形成吸积环。但即使质量比为2/3，环质量也约为太阳质量的10%。(4)在黑洞形成的最后时刻，伴随着准正规模振铃的引力波被发射出来，在50 Mpc的距离上，振幅约为10^<-23>，频率约为7 kHz。要探测到这样的引力波是非常困难的，除非我们的银河系碰巧发生了合并。(5)在HMNS形成的情况下，由于椭圆HMNS的旋转而发射准周期引力波。在50 Mpc的距离处，有效振幅约为10 Ω<-20>，频率约为3 kHz。这样的引力波可能会被下一代探测器探测到。(6)不等质量双星合并后，形成一个被大质量环面包围的黑洞。该系统是伽玛暴中心引擎的候选者。少

项目成果

期刊论文数量（20）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Merger of binary stars to a black hole : Disk mass, short gamma-ray bursts, and quasinormal mode ringing

双星合并到黑洞：盘质量、短伽马射线爆发和准正模振铃

DOI：
发表时间：
2006
期刊：
Physical Review D73
影响因子：
0
作者：
M.Shibata;K.Taniguchi
通讯作者：
K.Taniguchi

Merger of binary neutron stars with realistic equations of state in full general relativity

DOI：
10.1103/physrevd.71.084021
发表时间：
2005-03
期刊：
Physical Review D
影响因子：
5
作者：
M. Shibata;K. Taniguchi;K. Uryū
通讯作者：
M. Shibata;K. Taniguchi;K. Uryū

Merger of black hole-neutron star binaries : Nonspinnig black hole case

黑洞与中子星双星的合并：非自旋黑洞情况

DOI：
发表时间：
2006
期刊：
Physical Review D 74
影响因子：
0
作者：
Masato Minamitsuji;Wade Naylor and Misao Sasaki;佐々木節;南辻真人;Christian T. Byrnes;小玉英雄;横山順一;Robert Brandenberger;白水徹也;横山修一郎;Antonino Flachi;柴田大
通讯作者：
柴田大

Magnetorotational collapse of massive stellar cores to neutron stars : Simulation in full general relativity

大质量恒星核心磁旋转塌缩成中子星：完全广义相对论的模拟