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arXiv 0908.3814gr-qc
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探测黑洞模拟的穿刺

Probing the puncture for black hole simulations

J. David Brown

摘要:

利用黑洞模拟的穿刺方法,将虫洞几何的第二无限域压缩为计算网格上的一个穿刺点。穿刺周围的区域迅速演变为喇叭形几何形状。计算网格只覆盖了喇叭喉的一部分。它终止于边界,边界的位置取决于分辨率。这就提出了一种可能性,即喇叭形几何中的扰动可以沿着喇叭形喉部传播,从穿刺边界反射,并以分辨率依赖的时间延迟返回黑洞外部。未观察到这种病理行为。这是解释的观察,一些微扰模式传播的共形几何,其他传播的物理几何。穿刺边界仅存在于物理几何体中。在物理几何结构中传播的模式总是在穿孔边界处被引导远离计算域。有限差分格式确保这些模式通过边界平流,而不耦合到在共形几何形状中传播的模式。这些结果得到了数值实验的支持,与标准的笛卡尔有限差分格式的球对称引力场的发展代码。该代码使用鲍姆加特-夏皮罗-柴田-中村制定爱因斯坦方程与1+日志切片和伽马-驱动器移位条件。

英文摘要:

With the puncture method for black hole simulations, the second infinity of a wormhole geometry is compactified to a single "puncture point" on the computational grid. The region surrounding the puncture quickly evolves to a trumpet geometry. The computational grid covers only a portion of the trumpet throat. It ends at a boundary whose location depends on resolution. This raises the possibility that perturbations in the trumpet geometry could propagate down the trumpet throat, reflect from the puncture boundary, and return to the black hole exterior with a resolution--dependent time delay. Such pathological behavior is not observed. This is explained by the observation that some perturbative modes propagate in the conformal geometry, others propagate in the physical geometry. The puncture boundary exists only in the physical geometry. The modes that propagate in the physical geometry are always directed away from the computational domain at the puncture boundary. The finite difference stencils ensure that these modes are advected through the boundary with no coupling to the modes that propagate in the conformal geometry. These results are supported by numerical experiments with a code that evolves spherically symmetric gravitational fields with standard Cartesian finite difference stencils. The code uses the Baumgarte--Shapiro--Shibata--Nakamura formulation of Einstein's equations with 1+log slicing and gamma--driver shift conditions.

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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