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arXiv 1407.7407gr-qccs.NAmath.APmath.NA
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数值与解析方法用于渐近平坦时空

Numerical and analytical methods for asymptotically flat spacetimes

Max Planck Institute for Gravitational Physics (Albert Einstein Institute)(马克斯·普朗克引力物理研究所(阿尔伯特·爱因斯坦研究所));Freie Universität Berlin(柏林自由大学)

Oliver Rinne

AI总结:

本文探讨了处理无限延伸渐近平坦时空的两种方法,包括基于Cauchy超曲面的数值方法和超曲面方法,分析了约束保持边界条件及引力辐射的定义。

摘要:

本文首先为应用数学背景的读者简要介绍数值相对论。随后介绍了处理无限延伸渐近平坦时空的研究所采用的两种方法:第一种基于在Cauchy超曲面上的演化并引入人工时间边界,分析了广义谐波 gauge 中爱因斯坦方程的约束保持边界条件的适定性,比较了不同方法的数值表现,并构建了改进的吸收边界条件。第二种方法则是在超曲面(渐近特征)上求解爱因斯坦方程,这些超曲面通过未来null无穷远处的共形压缩,明确定义了引力辐射。展示了在3+1分解中形式奇异项在未来null无穷远处的评估方法,展示了真空轴对称黑洞时空的稳定数值演化,并研究了球对称物质场的晚期时间幂律尾部。

英文摘要:

This article begins with a brief introduction to numerical relativity aimed at readers who have a background in applied mathematics but not necessarily in general relativity. I then introduce and summarise my work on the problem of treating asymptotically flat spacetimes of infinite extent with finite computational resources. Two different approaches are considered. The first approach is the standard one and is based on evolution on Cauchy hypersurfaces with artificial timelike boundary. The well posedness of a set of constraint-preserving boundary conditions for the Einstein equations in generalised harmonic gauge is analysed, their numerical performance is compared with various alternate methods, and improved absorbing boundary conditions are constructed and implemented. In the second approach, one solves the Einstein equations on hyperboloidal (asymptotically characteristic) hypersurfaces. These are conformally compactified towards future null infinity, where gravitational radiation is defined in an unambiguous way. We show how the formally singular terms arising in a $3+1$ reduction of the equations can be evaluated at future null infinity, present stable numerical evolutions of vacuum axisymmetric black hole spacetimes and study late-time power-law tails of matter fields in spherical symmetry.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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