Through numerical simulations, it is predicted that the gravitational waves (GWs) reflect the characteristics of the core-collapse supernova (CCSN) explosion mechanism. There are multiple GW excitation processes that occur inside a star before its explosion, and it is suggested that the GWs originating from the CCSN have a mode for each excitation process in terms of time-frequency representation. Therefore, we propose an application of the Hilbert-Huang transform (HHT), which is a high-resolution time-frequency analysis method, to analyze these GW modes for theoretically probing and increasing our understanding of the explosion mechanism. The HHT defines frequency as a function of time, and is not bound by the trade-off between time and frequency resolutions. In this study, we analyze a gravitational waveform obtained from a three-dimensional general-relativistic CCSN model that showed a vigorous activity of the standing-accretion-shock-instability (SASI). We succeed in extracting the SASI induced GWs with high resolution on a time-frequency representation using the HHT and we examine their instantaneous frequencies.

中文翻译：

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Hilbert-Huang 变换在核塌陷超新星中驻留吸积冲击不稳定诱导引力波分析中的应用

通过数值模拟，预测引力波（GWs）反映了核心坍缩超新星（CCSN）爆炸机制的特征。一颗恒星在爆炸前会发生多次引力波激发过程，建议源自CCSN的引力波在时频表示上对每个激发过程都有一个模式。因此，我们建议应用 Hilbert-Huang 变换（HHT），这是一种高分辨率的时频分析方法，来分析这些 GW 模式，以从理论上探索并增加我们对爆炸机制的理解。HHT 将频率定义为时间的函数，并且不受时间和频率分辨率之间折衷的限制。在这项研究中，我们分析了从三维广义相对论 CCSN 模型获得的引力波形，该模型显示了立吸积冲击不稳定性 (SASI) 的剧烈活动。我们成功地使用 HHT 在时频表示上以高分辨率提取了 SASI 诱导的 GW，并检查了它们的瞬时频率。