The Peculiar Precursor of a Gamma-Ray Burst from a Binary Merger Involving a Magnetar

• Published in: arXiv.org 2024-07
• Main Authors: Xiao, Shuo, Yan-Qiu, Zhang, Zi-Pei Zhu, Shao-Lin, Xiong, Gao, He, Xu, Dong, Zhang, Shuang-Nan, Wen-Xi, Peng, Xiao-Bo, Li, Zhang, Peng, Fang-Jun, Lu, Lin, Lin, Liang-Duan, Liu, Zhang, Zhen, Ming-Yu, Ge, You-Li, Tuo, Wang-Chen, Xue, Shao-Yu, Fu, Liu, Xing, Jin-Zhong, Liu, Li, An, Tian-Cong, Wang, Zheng, Chao, Wang, Yue, Shuai-Qing Jiang, Jin-Da, Li, Jia-Cong, Liu, Zhou-Jian, Cao, Xi-Hong, Luo, Jiao-Jiao, Yang, Shu-Xu, Yi, Xi-Lu, Wang, Cai, Ce, Qi-Bin, Yi, Zhao, Yi, Sheng-Lun Xie, Cheng-Kui, Li, Luo, Qi, Li-Ming, Song, Zhang, Shu, Jin-Lu, Qu, Cong-Zhan, Liu, Xu-Fang, Li, Yu-Peng, Xu, Ti-Pei Li
• Format: Article
• Language: English
• Subjects: Binary stars; Black holes; Gamma ray astronomy; Gamma ray bursts; Gravitational waves; Magnetars; Neutron stars; Neutrons; Precursors; Quasi-Periodic Oscillations; Star mergers
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2205.02186

The milestone discovery of GW 170817-GRB 170817A-AT 2017gfo has shown that gravitational wave (GW) could be produced during the merger of neutron star-neutron star/black hole and that in electromagnetic (EM) wave a gamma-ray burst (GRB) and a kilonova (KN) are generated in sequence after the merger. Observationally, however, EM property before the merger phase is still unclear. Here we report a peculiar precursor in a KN-associated long-duration GRB 211211A, providing evidence of the EM before the merger. This precursor lasts \(\sim\) 0.2 s, and the waiting time between the precursor and the main burst is \(\sim\) 1 s, comparable to that between GW 170817 and GRB 170817A. The spectrum of the precursor could be well fit with a non-thermal cutoff power-law model instead of a blackbody. Especially, a \(\sim\)22 Hz Quasi-Periodic Oscillation candidate (\(\sim 3\sigma\)) is detected in the precursor. These temporal and spectral properties indicate that this precursor is probably produced by a catastrophic flare accompanying with magnetoelastic or crustal oscillations of a magnetar in binary compact merger. The strong magnetic field of the magnetar can also account for the prolonged duration of GRB 211211A. However, it poses a challenge to reconcile the rather short lifetime of a magnetar with the rather long spiraling time of a binary neutron star system only by the GW radiation before merger.