The main features of the gravitational dynamics of binary neutron star systems are now well established. While the inspiral can be precisely described in the post-Newtonian approximation, fully relativistic magneto-hydrodynamical simulations are required to model the evolution of the merger and post-merger phase. However, the interpretation of the numerical results can often be non-trivial, so that toy models become a very powerful tool. Not only do they simplify the interpretation of the post-merger dynamics, but also allow to gain insights into the physics behind it. In this work, we construct a simple toy model that is capable of reproducing the whole angular momentum evolution of the post-merger remnant, from the merger to the collapse. We validate the model against several fully general-relativistic numerical simulations employing a genetic algorithm, and against additional constraints derived from the spectral properties of the gravitational radiation. As a result, from the remarkably close overlap between the model predictions and the reference simulations within the first milliseconds after the merger, we are able to systematically shed light on the currently open debate regarding the source of the low-frequency peaks of the gravitational wave power spectral density. Additionally, we also present two original relations connecting the angular momentum of the post-merger remnant at merger and collapse to initial properties of the system.

现在已经很好地建立了双星中子星系统的引力动力学的主要特征。虽然可以在牛顿后近似中精确描述吸气，但仍需要完全相对论的磁流体动力学模拟来模拟合并和合并后阶段的演变。但是，对数值结果的解释通常很简单，因此玩具模型成为非常强大的工具。它们不仅简化了合并后动力学的解释，而且还使您能够洞悉其背后的物理原理。在这项工作中，我们构建了一个简单的玩具模型，该模型能够重现合并后残骸从合并到崩溃的整个角动量演化。我们通过使用遗传算法的几个完全相对论的数值模拟，以及从重力辐射的光谱特性得出的其他约束条件，对模型进行了验证。结果，由于合并后的最初几毫秒内模型预测与参考模拟之间的紧密重叠，我们能够系统地阐明有关引力波低频峰源的当前公开辩论功率谱密度。此外，我们还提出了两个原始关系，将合并和崩溃时合并后残留的角动量与系统的初始属性联系起来。从合并后的几毫秒内模型预测与参考模拟之间的显着重叠非常明显，我们能够系统地阐明有关引力波功率谱密度低频峰源的当前公开辩论。此外，我们还提出了两个原始关系，将合并和崩溃时合并后残留的角动量与系统的初始属性联系起来。从合并后的几毫秒内模型预测与参考模拟之间的显着重叠非常明显，我们能够系统地阐明有关引力波功率谱密度低频峰源的当前公开辩论。此外，我们还提出了两个原始关系，将合并和崩溃时合并后残留的角动量与系统的初始属性联系起来。