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Coalescence of Binary Neutron Stars and Gravitational Radiation

双中子星的聚结和引力辐射

基本信息

批准号：
13640271
负责人：
OOHARA Ken-ichi
金额：
$ 1.28万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640271/
关键词：
General Relativity Gravitational Waves Neutron Star Numerical Simulation

项目摘要

We have performed numerical simulations for coalescing binary neutron stars using a 3-dimensional general relativistic code and investigate radiation of gravitational waves. A stable code using maximal slicing and pseudo-minimal distortion condition has been obtained, where we found that it is important to calculate the second-derivative of the metric tensor with precision making use of the pseudo-minimal distortion condition. At first, some parts of the gravitational waves are reflected at the numerical boundary, but it is found to be fixed if the grid size is enlarged. We use a 475 × 475 grid in the Cartesian coordinate system. The CPU hours necessary to perform the simulation for each parameter set is approximately 100 hours on Fujitsu VPP5000 with 32 nodes.To evaluate the gravitational radiation, we implemented a gauge-invariant wave extraction and compared the wave forms with a simple estimate of waves from metric perturbation. The energy spectrum of the waves was also evaluated to investigate the possibility that the excitation of the quasi-normal modes of black hole, which may be formed after merger of two stars, can be caught. However, we need more precise calculation with finer grid and larger grid size from various initial data to obtain definite results.The following revision of the code remains for future research; more realistic initial data and other method of gauge-invariant wave extraction. The required CPU hours will be reduced if slightly different coordinate conditions are used.

我们用三维广义相对论程序对合并中子星进行了数值模拟，并研究了引力波辐射。利用最大切片和伪最小失真条件得到了一个稳定的编码，其中我们发现利用伪最小失真条件精确计算度量张量的二阶导数是很重要的.初始时，部分引力波在数值边界处被反射，但随着网格尺寸的增大，这部分引力波被固定下来。我们在笛卡尔坐标系中使用475 × 475网格。每个参数集的模拟所需的CPU时间约为100小时富士通VPP 5000与32 nodes.To评估的引力辐射，我们实现了规范不变的波提取和比较的波形与一个简单的估计波从度规扰动。并对波的能谱进行了计算，以探讨两星合并后黑洞准简正模激发被捕获的可能性。然而，我们需要更精确的计算，更细的网格和更大的网格尺寸从各种初始数据，以获得明确的结果。以下的代码的修订仍有待于未来的研究，更现实的初始数据和其他方法的规范不变的波提取。如果使用稍微不同的坐标条件，所需的CPU时间将减少。