Bishop Nigel T, Rezzolla Luciano
Department of Mathematics, Rhodes University, Grahamstown, 6140 South Africa.
Institute for Theoretical Physics, 60438 Frankfurt am Main, Germany ; Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany.
Living Rev Relativ. 2016;19(1):2. doi: 10.1007/s41114-016-0001-9. Epub 2016 Oct 4.
A numerical-relativity calculation yields in general a solution of the Einstein equations including also a radiative part, which is in practice computed in a region of finite extent. Since gravitational radiation is properly defined only at null infinity and in an appropriate coordinate system, the accurate estimation of the emitted gravitational waves represents an old and non-trivial problem in numerical relativity. A number of methods have been developed over the years to "extract" the radiative part of the solution from a numerical simulation and these include: quadrupole formulas, gauge-invariant metric perturbations, Weyl scalars, and characteristic extraction. We review and discuss each method, in terms of both its theoretical background as well as its implementation. Finally, we provide a brief comparison of the various methods in terms of their inherent advantages and disadvantages.
数值相对论计算通常会得出爱因斯坦方程的一个解，其中还包括一个辐射部分，实际上这个辐射部分是在有限范围的区域内计算出来的。由于引力辐射仅在零无穷远处并在适当的坐标系中才有恰当的定义，所以对发射出的引力波进行精确估计在数值相对论中是一个由来已久且并非轻而易举的问题。多年来已经开发出了许多方法来从数值模拟中“提取”解的辐射部分，这些方法包括：四极公式、规范不变度规微扰、外尔标量以及特征提取。我们将从理论背景及其实现两个方面对每种方法进行回顾和讨论。最后，我们简要比较各种方法的固有优缺点。
