Numerical relativists can now produce gravitational waveforms with memory effects routinely and accurately. The gravitational-wave memory effect contains very low-frequency components, including a persistent offset. The presence of these components violates basic assumptions about time-shift behavior underpinning standard data-analysis techniques in gravitational-wave astronomy. This poses a challenge to the analysis of waveform spectra: how to preserve the low-frequency characteristics when transforming a time-domain waveform to the frequency domain. To tackle this challenge, we revisit the preprocessing procedures applied to the waveforms that contain memory effects. We find inconsistency between the zero-frequency limit of displacement memory and the low-frequency spectrum of the same memory preprocessed using the common scheme in literature. To resolve the inconsistency, we propose a new robust preprocessing scheme that produces the spectra of memory waveforms more faithfully. Using this new scheme, we inspect several characteristics of the spectrum of a memory waveform. In particular, we find a discernible beating pattern formed by the dominant oscillatory mode and the displacement memory. This pattern is absent in the spectrum of a waveform without memory. The difference between the memory and no-memory waveforms is too small to be observed by current-generation detectors in a single binary-black-hole event. Detecting the memory in a single event is likely to occur in the era of next-generation detectors.

中文翻译：

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在双黑洞模拟中改进了带有记忆的引力波频谱


数值相对论者现在可以常规、准确地产生具有记忆效应的引力波形。引力波记忆效应包含非常低频的成分，包括持续偏移。这些成分的存在违反了关于时移行为的基本假设，而时移行为是引力波天文学中标准数据分析技术的基础。这给波形频谱分析提出了挑战：如何在将时域波形变换到频域时保留低频特性。为了应对这一挑战，我们重新审视应用于包含记忆效应的波形的预处理程序。我们发现位移存储器的零频率极限与使用文献中的通用方案预处理的同一存储器的低频频谱之间不一致。为了解决这种不一致问题，我们提出了一种新的鲁棒预处理方案，可以更忠实地生成内存波形的频谱。使用这种新方案，我们检查了存储器波形频谱的几个特征。特别是，我们发现了由主导振荡模式和位移记忆形成的可辨别的跳动模式。在没有记忆的波形频谱中不存在这种模式。记忆波形和非记忆波形之间的差异太小，无法通过当前一代探测器在单个双黑洞事件中观察到。在单个事件中检测记忆很可能发生在下一代探测器的时代。