학술논문
Individual and Averaged Power Density Spectra of X-ray bursts from SGR J1935+2154: Quasiperiodic Oscillation Search and Slopes
Document Type
Working Paper
Author
Xiao, Shuo; Li, Xiao-Bo; Xue, Wang-Chen; Xiong, Shao-Lin; Zhang, Shuang-Nan; Peng, Wen-Xi; Dong, Ai-Jun; Tuo, You-Li; Cai, Ce; Luo, Xi-Hong; Yang, Jiao-Jiao; Wang, Yue; Zheng, Chao; Zhang, Yan-Qiu; Liu, Jia-Cong; Tan, Wen-Jun; Wang, Chen-Wei; Wang, Ping; Li, Cheng-Kui; Yi, Shu-Xu; Dang, Shi-Jun; Shang, Lun-Hua; Zhao, Ru-Shuang; Ma, Qing-Bo; Xie, Wei; Feng, Jian-Chao; Zhang, Bin; Zhang, Zhen; Ge, Ming-Yu; Zheng, Shi-Jie; Song, Li-Ming; Zhi, Qi-Jun
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Abstract
The study of quasi-periodic oscillations (QPOs) and power density spectra (PDS) continuum properties can help shed light on the still illusive emission physics of magnetars and as a window into the interiors of neutron stars using asteroseismology. In this work, we employ a Bayesian method to search for the QPOs in the hundreds of X-ray bursts from SGR J1935+2154 observed by {\it Insight}-HXMT, GECAM and Fermi/GBM from July 2014 to January 2022. Although no definitive QPO signal (significance $>3\sigma$) is detected in individual bursts or the averaged periodogram of the bursts grouped by duration, we identify several bursts exhibiting possible QPO at $\sim$ 40 Hz, which is consistent with that reported in the X-ray burst associated with FRB 200428. We investigate the PDS continuum properties and find that the distribution of the PDS slope in the simple power-law model peaks $\sim$ 2.5, which is consistent with other magnetars but higher than 5/3 commonly seen in gamma-ray bursts. Besides, the distribution of the break frequency in the broken power-law model peaks at $\sim$ 60 Hz. Finally, we report that the power-law index of PDS has an anti-correlation and power-law dependence on the burst duration as well as the minimum variation timescale.
Comment: comments welcome
Comment: comments welcome