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arXiv 0912.1285gr-qcastro-ph.COastro-ph.HE
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数值相对论中的特征提取:零无穷远处的二元黑洞合并波形

Characteristic extraction in numerical relativity: binary black hole merger waveforms at null infinity

C. Reisswig, N. T. Bishop, D. Pollney, B. Szilagyi

摘要:

引力辐射的精确模拟是引力波天文学的关键问题。随着模拟代码达到更高的精度,当前数值相对论波提取方法中固有的系统误差变得明显,并可能导致对数据的错误天体物理解释。在本文中,我们给出了一个详细的描述的柯西特征提取技术应用于二进制黑洞螺旋和合并的演变,以获得引力波形的定义明确,即在未来的零无穷大。通过这种方法,我们消除了有限半径近似和需要从近区外推数据。此外,我们证明了该方法是免费的规范效应,因此只受数值误差。各种一致性检查表明,能量和角动量守恒到高精度,并与外推数据非常一致。此外,我们重新计算了引力反冲,发现有限半径外推法很好地近似了$\scri$的结果。然而,外推数据的(非收敛)系统差异与柯西演化的(收敛)离散化误差具有相同的数量级,因此突出了正确提取波的必要性。

英文摘要:

The accurate modeling of gravitational radiation is a key issue for gravitational wave astronomy. As simulation codes reach higher accuracy, systematic errors inherent in current numerical relativity wave-extraction methods become evident, and may lead to a wrong astrophysical interpretation of the data. In this paper, we give a detailed description of the Cauchy-characteristic extraction technique applied to binary black hole inspiral and merger evolutions to obtain gravitational waveforms that are defined unambiguously, that is, at future null infinity. By this method we remove finite-radius approximations and the need to extrapolate data from the near zone. Further, we demonstrate that the method is free of gauge effects and thus is affected only by numerical error. Various consistency checks reveal that energy and angular momentum are conserved to high precision and agree very well with extrapolated data. In addition, we revisit the computation of the gravitational recoil and find that finite radius extrapolation very well approximates the result at $\scri$. However, the (non-convergent) systematic differences to extrapolated data are of the same order of magnitude as the (convergent) discretisation error of the Cauchy evolution hence highlighting the need for correct wave-extraction.

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