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arXiv 1507.07100gr-qcastro-ph.HEastro-ph.SR
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具有类属自旋、偏心率、质量比和致密性的中子星双星--准平衡序列和第一次演化

Binary Neutron Stars with Generic Spin, Eccentricity, Mass ratio, and Compactness - Quasi-equilibrium Sequences and First Evolutions

Tim Dietrich, Niclas Moldenhauer, Nathan K. Johnson-McDaniel, Sebastiano Bernuzzi, Charalampos M. Markakis, Bernd Bruegmann, Wolfgang Tichy

摘要:

从准平衡位形和动力学演化中可以提取出关于中子星涡卷最后阶段和最终合并的信息。在这篇文章中,我们构造了不同自旋、偏心率、质量比、紧度和状态方程的准平衡组态。为此,我们采用SGRID代码,它允许我们在以前无法访问的参数空间区域中构建这样的数据。特别是,我们考虑自旋中子星在隔离和二进制系统中,我们采用新的方法来产生高度偏心和偏心率减少的数据,我们提出了计算数据的可能性显着不等质量的二进制文件,我们创建等质量的二进制文件与个人的紧凑性高达0.23。作为一个原则的证明,我们探讨了三个新的配置的动力学演化。首先,我们模拟了一个$q=2.06$质量比,这是迄今为止在数值相对论中演化的二元中子星的最高质量比。我们发现,从伴星的质量转移集在合并前的几个革命和$\sim10^{-2}M_\odot$的静止质量之间转移的两颗星。在合并过程中,这种结构也会蒸发大量的物质,对残余物产生很大的反冲。其次,我们模拟了进动双星中子星的第一次合并。我们给出了用于进动模拟的引力波的主导模式,其中在(2,1)模式中可以看到明显的进动印记。最后,我们量化的偏心减少程序的重力波形的影响。该程序提高了波形质量,并应在未来的精度研究中使用,但也需要减少其他误差,特别是截断误差,以使偏心率降低所带来的改善有效。[删节]

英文摘要:

Information about the last stages of a binary neutron star inspiral and the final merger can be extracted from quasi-equilibrium configurations and dynamical evolutions. In this article, we construct quasi-equilibrium configurations for different spins, eccentricities, mass ratios, compactnesses, and equations of state. For this purpose we employ the SGRID code, which allows us to construct such data in previously inaccessible regions of the parameter space. In particular, we consider spinning neutron stars in isolation and in binary systems; we incorporate new methods to produce highly eccentric and eccentricity reduced data; we present the possibility of computing data for significantly unequal-mass binaries; and we create equal-mass binaries with individual compactness up to 0.23. As a proof of principle, we explore the dynamical evolution of three new configurations. First, we simulate a $q=2.06$ mass ratio which is the highest mass ratio for a binary neutron star evolved in numerical relativity to date. We find that mass transfer from the companion star sets in a few revolutions before merger and a rest mass of $\sim10^{-2}M_\odot$ is transferred between the two stars. This configuration also ejects a large amount of material during merger, imparting a substantial kick to the remnant. Second, we simulate the first merger of a precessing binary neutron star. We present the dominant modes of the gravitational waves for the precessing simulation, where a clear imprint of the precession is visible in the (2,1) mode. Finally, we quantify the effect of an eccentricity reduction procedure on the gravitational waveform. The procedure improves the waveform quality and should be employed in future precision studies, but also other errors, notably truncation errors, need to be reduced in order for the improvement due to eccentricity reduction to be effective. [abridged]

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