Hilbert–Huang Transform Analysis of Quasiperiodic Oscillations in MAXI J1820+070
Hilbert–Huang Transform Analysis of Quasiperiodic Oscillations in MAXI J1820+070
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DOI：
10.3847/1538-4357/acd756
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发表时间：
2023-05
期刊：
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通讯作者：
Wei Yu;Q. Bu;Zijian Yang;He Liu;Liang Zhang;Yue Huang;D. Zhou;J. Qu;S. Zhang;Shu Zhang;Lingming Song;S. Jia;Xiang Ma;L. Tao;Mingyang Ge;Qing-zhong Liu;Jing Yan
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作者：
Wei Yu;Q. Bu;Zijian Yang;He Liu;Liang Zhang;Yue Huang;D. Zhou;J. Qu;S. Zhang;Shu Zhang;Lingming Song;S. Jia;Xiang Ma;L. Tao;Mingyang Ge;Qing-zhong Liu;Jing Yan
本文基于Hilbert-Huang变换，对X射线双星MAXI J1820+070中观测到的低频准周期振荡的演化进行了时频分析。通过经验模分解方法，我们分解了准周期振荡（QPO）分量的光变曲线，并测量了不同能带光子之间的本征相位滞后。我们发现QPO相位滞后是负的（低能光子滞后于高能光子），同时，滞后的绝对值随能量的增加而增加。通过对QPO的光变曲线进行希尔伯特变换，我们进一步提取了QPO的瞬时频率和振幅。将这些结果与傅里叶分析的结果进行比较，我们发现QPO峰的展宽主要是由频率调制引起的。通过进一步分析，我们发现这些调制与宽带噪声有着共同的物理根源，并且可以用喷流的内激波模型得到很好的解释。
We present a time-frequency analysis, based on the Hilbert–Huang transform, of the evolution of the low-frequency quasiperiodic oscillations observed in the black hole X-ray binary MAXI J1820+070. Through the empirical mode decomposition method, we decompose the light curve of the quasiperiodic oscillation (QPO) component and measure its intrinsic phase lag between photons from different energy bands. We find that the QPO phase lag is negative (low-energy photons lag behind high-energy photons); meanwhile, the absolute value of the lag increases with energy. By applying the Hilbert transform to the light curve of the QPO, we further extract the instantaneous frequency and amplitude of the QPO. Comparing these results with those from the Fourier analysis, we find that the broadening of the QPO peak is mainly caused by frequency modulation. Through further analysis, we find that these modulations could share a common physical origin with the broadband noise, and can be well explained by the internal shock model of the jet.