GRB 220408B: A Three-Episode Burst from a Precessing Jet

Zijian Zhang; Yihan Yin; Chenyu Wang; Xiangyu Ivy Wang; Jun Yang; Yan-Zhi Meng; Zi-Ke Liu; Guo-Yin Chen; Xiaoping Fu; Huaizhong Gao; Sihao Li; Yihui Liu; Xiangyun Long; Yong-Chang Ma; Xiaofan Pan; Yuanze Sun; Wei Wu; Zirui Yang; Zhizhen Ye; Xiaoyu Yu; Shuheng Zhao; Xutao Zheng; Tao Zhou; Qing-Wen Tang; Qiurong Yan; Rong Zhou; Zhonghai Wang; Hua Feng; Ming Zeng; Bin-Bin Zhang

arXiv · 2302.03215

GRB 220408B: A Three-Episode Burst from a Precessing Jet

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Abstract

Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts (GRBs). In this {\it Letter}, we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model. As one of the recently confirmed GRBs observed by our GRID CubeSat mission, GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes. Furthermore, the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags. Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay (FRED) shape light curve intrinsically produced by a precessing jet with a precession period of $18.4 \pm 0.2$ seconds, a nutation period of $11.1 \pm 0.2$ seconds and viewed off-axis. This study provides a straightforward explanation for the complex yet similar multi-episode GRB light curves.

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Zijian Zhang, Yihan Yin, Chenyu Wang, Xiangyu Ivy Wang, Jun Yang, Yan-Zhi Meng, Zi-Ke Liu, Guo-Yin Chen, Xiaoping Fu, Huaizhong Gao, Sihao Li, Yihui Liu, Xiangyun Long, Yong-Chang Ma, Xiaofan Pan, Yuanze Sun, Wei Wu, Zirui Yang, Zhizhen Ye, Xiaoyu Yu, Shuheng Zhao, Xutao Zheng, Tao Zhou, Qing-Wen Tang, Qiurong Yan, Rong Zhou, Zhonghai Wang, Hua Feng, Ming Zeng, Bin-Bin Zhang. 2023-02-07. GRB 220408B: A Three-Episode Burst from a Precessing Jet. https://arxiv.org/abs/2302.03215

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