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arXiv 2301.05413gr-qc
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Bondi-Sachs规范中的保约束边界条件:纯AdS时空稳定性的数值研究

Constraint preserving boundary conditions in Bondi-Sachs gauge: a numerical study of stability of pure AdS spacetime

Li-Ming Cao, Liang-Bi Wu, Yu-Sen Zhou

摘要:

在Bondi-Sachs规范下,将具有宇宙学常数的Einstein方程与球对称的标量场耦合,转化为一阶强双曲方程,其中的时滞和位移是基本变量.在该方程组中,位移和位移是输入特征场,而标量场有三种模式:输入模式、输出模式和静态模式。利用Bianchi恒等式构造了一个保约束的初边值问题。利用这个方案,我们发现在足够远的边界处,标量场的任何微小扰动都能引起纯AdS时空的坍缩,并为视视界的形成提供了数值证据.数值演化是用标准的线方法,在空间和时间上的二阶。演化采用标准的二阶龙格-库塔法,空间离散导数采用二阶中心差分,四阶人工耗散。

英文摘要:

In the Bondi-Sachs gauge, the Einstein equations with a cosmological constant coupled to a scalar field in spherical symmetry are cast into a first order strongly hyperbolic formulation in which the lapse and shift are the fundamental variables. For this system of equations, the lapse and shift are ingoing characteristic fields, and the scalar field has three modes: ingoing, outgoing and static, respectively. A constraint-preserving initial boundary value problem is constructed by using Bianchi identity. Using this scheme, we find that any small perturbation of the scalar field at the boundary far away enough can cause the collapse of the pure AdS spacetime, and we provide the numerical evidence for the formation of apparent horizons. The numerical evolution is performed with a standard method of lines, second order in space and time. The evolution is performed using the standard second order Runge-Kutta method while the space discrete derivative is second order central difference with fourth order artificial dissipation.

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