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arXiv 1306.5976gr-qc
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约束演化公式中黑洞的一个切除方案:球对称情形

An excision scheme for black holes in constrained evolution formulations: spherically symmetric case

Isabel Cordero-Carrión, Nicolas Vasset, Jérôme Novak, José Luis Jaramillo

摘要:

切除技术是用来处理黑洞在爱因斯坦方程的数值模拟,并包括在删除一个拓扑球包含的物理奇点从数值域,而不是适用于适当的边界条件切除表面。在这项工作中,我们提出了这种技术的情况下,爱因斯坦方程和球对称时空的约束配方的最新发展。在Bonazzola等人(2004)的完全约束形式中,我们提出了一组新的边界条件,适用于视视界内的任意坐标球上的椭圆系统。这个系统的边界条件的分析性质进行了研究,并在一定的假设下,指数收敛到静态解的真空时空。这一点在数值例子中得到了验证,同时也证明了该方法在Schwarzschild黑洞吸积标量场的情况下的适用性。我们还提出了成功地使用切除技术在一个中子星的黑洞的崩溃,当切除是在模拟过程中打开,形成后的视视界。这使得物质的吸积保留在切除表面和稳定的长期演化的新形成的黑洞。

英文摘要:

Excision techniques are used in order to deal with black holes in numerical simulations of Einstein equations and consist in removing a topological sphere containing the physical singularity from the numerical domain, applying instead appropriate boundary conditions at the excised surface. In this work we present recent developments of this technique in the case of constrained formulations of Einstein equations and for spherically symmetric spacetimes. We present a new set of boundary conditions to apply to the elliptic system in the fully-constrained formalism of Bonazzola et al. (2004), at an arbitrary coordinate sphere inside the apparent horizon. Analytical properties of this system of boundary conditions are studied and, under some assumptions, an exponential convergence toward the stationary solution is exhibited for the vacuum spacetime. This is verified in numerical examples, together with the applicability in the case of the accretion of a scalar field onto a Schwarzschild black hole. We also present the successful use of the excision technique in the collapse of a neutron star to a black hole, when excision is switched on during the simulation, after the formation of the apparent horizon. This allows the accretion of matter remaining outside the excision surface and for the stable long-term evolution of the newly formed black hole.

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