Simulating coalescing compact binaries by a new code (SACRA)
Simulating coalescing compact binaries by a new code (SACRA)
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DOI：
10.1103/physrevd.78.064054
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发表时间：
2008-06
影响因子：
5
通讯作者：
Tetsuro Yamamoto;M. Shibata;K. Taniguchi
中科院分区：
文献类型：
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作者：
Tetsuro Yamamoto;M. Shibata;K. Taniguchi
我们报告我们的新代码，名为SACRA（SimulAtor的紧凑对象在相对论天体物理学）的数值相对论模拟，其中实现了自适应网格细化算法。在该程序中，爱因斯坦方程采用Baumgarte-Shapiro-Shibata-Nakamura格式，采用四阶差分格式求解，流体力学方程采用三阶高分辨率中心格式求解。时间积分采用四阶龙格-库塔格式。为了验证该程序的有效性，分别对黑洞-黑洞、中子星-中子星星（NS-NS）和黑洞-中子星星（BH-NS）双星的合并过程进行了模拟，并对这三种情况下合并后形成的黑洞的性质和引力波形进行了比较。对于黑洞-黑洞双星的模拟，我们采用与Buonanno等人相同的初始条件，并比较数值结果。我们发现合理的协议，除了轻微的分歧可能与不同的规范条件和数值方案的选择。对于一个NS-NS双星，我们使用SACRA和柴田以前的程序进行了模拟，并发现两个数值结果之间的最终结果和重力波形的定性性质合理的协议。我们还发现，NS-NSmore »二进制的数值结果收敛相对较慢，并再次意识到需要使用多种分辨率和网格设置进行长期数值模拟来验证结果。对于BH-NS双星，我们将数值计算结果与前人的结果进行了比较，发现合并后形成的BH的引力波形和性质与前人的结果一致，尽管合并后形成的盘质量小于总静止质量的0.1%，这与前人的结果不一致。我们还报告的长期模拟（约4个轨道）的BH-NS二进制的第一次的数值结果。所有这些数值计算结果表明收敛的行为，和外推的数值结果的时间内螺旋相同意后牛顿预测在一个合理的精度。这些事实验证了SACRA的结果。«少
We report our new code, named SACRA (SimulAtor for Compact objects in Relativistic Astrophysics) for numerical relativity simulations in which an adaptive mesh refinement algorithm is implemented. In this code, the Einstein equations are solved in the Baumgarte-Shapiro-Shibata-Nakamura formalism with a fourth-order finite differencing, and the hydrodynamic equations are solved by a third-order high-resolution central scheme. The fourth-order Runge-Kutta scheme is adopted for integration in time. To test the code, simulations for coalescence of black hole-black hole, neutron star-neutron star (NS-NS), and black hole-neutron star (BH-NS) binaries are performed, and also, properties of BHs formed after the merger and gravitational waveforms are compared among those three cases. For the simulations of black hole-black hole binaries, we adopt the same initial conditions as those by Buonanno et al. 1 and compare numerical results. We find reasonable agreement except for a slight disagreement possibly associated with the difference in choice of gauge conditions and numerical schemes. For an NS-NS binary, we performed simulations employing both SACRA and Shibata's previous code, and find reasonable agreement between two numerical results for the final outcome and qualitative property of gravitational waveforms. We also find that the convergence is relatively slow for numerical results of NS-NSmore » binaries, and again realize that long-term numerical simulations with several resolutions and grid settings are required for validating the results. For a BH-NS binary, we compare numerical results with our previous ones, and find that gravitational waveforms and properties of the BH formed after the merger agree well with those of our previous ones, although the disk mass formed after the merger is less than 0.1% of the total rest mass, which disagrees with the previous result. We also report numerical results of a long-term simulation (with {approx}4 orbits) for a BH-NS binary for the first time. All these numerical results show behavior of convergence, and extrapolated numerical results for time spent in the inspiral phase agree with post-Newtonian predictions in a reasonable accuracy. These facts validate the results by SACRA.« less