Bibliographic Details
| Title: |
Triggering the Untriggered: The First Einstein Probe-Detected Gamma-Ray Burst 240219A and Its Implications |
| Authors: |
Yin, Yi-Han Iris, Zhang, Bin-Bin, Yang, Jun, Sun, Hui, Zhang, Chen, Shao, Yi-Xuan, Hu, You-Dong, Zhu, Zi-Pei, Xu, Dong, An, Li, Gao, He, Wu, Xue-Feng, Zhang, Bing, Castro-Tirado, Alberto Javier, Pandey, Shashi B., Rau, Arne, Lei, Weihua, Xie, Wei, Ghirlanda, Giancarlo, Piro, Luigi, O'Brien, Paul, Troja, Eleonora, Jonker, Peter, Yu, Yun-Wei, An, Jie, Chen, Run-Chao, Chen, Yi-Jing, Dong, Xiao-Fei, Eyles-Ferris, Rob, Fan, Zhou, Fu, Shao-Yu, Fynbo, Johan P. U., Gao, Xing, Huang, Yong-Feng, Jiang, Shuai-Qing, Jiang, Ya-Hui, Julakanti, Yashaswi, Kuulkers, Erik, Lao, Qing-Hui, Li, Dongyue, Ling, Zhi-Xing, Liu, Xing, Liu, Yuan, Mou, Jia-Yu, Pan, Xin, Varun, Wei, Daming, Wu, Qinyu, Yadav, Muskan, Yang, Yu-Han, Yuan, Weimin, Zhang, Shuang-Nan |
| Source: |
2024, ApJL, 975, L27 |
| Publication Year: |
2024 |
| Collection: |
Astrophysics |
| Subject Terms: |
Astrophysics - High Energy Astrophysical Phenomena |
| More Details: |
The Einstein Probe (EP) achieved its first detection and localization of a bright X-ray flare, EP240219a, on 2024 February 19, during its commissioning phase. Subsequent targeted searches triggered by the EP240219a alert identified a faint, untriggered gamma-ray burst (GRB) in the archived data of Fermi Gamma-ray Burst Monitor (GBM), Swift Burst Alert Telescope (BAT), and Insight-HXMT/HE. The EP Wide-field X-ray Telescope (WXT) light curve reveals a long duration of approximately 160 s with a slow decay, whereas the Fermi/GBM light curve shows a total duration of approximately 70 s. The peak in the Fermi/GBM light curve occurs slightly later with respect to the peak seen in the EP/WXT light curve. Our spectral analysis shows that a single cutoff power-law (PL) model effectively describes the joint EP/WXT--Fermi/GBM spectra in general, indicating coherent broad emission typical of GRBs. The model yielded a photon index of $\sim -1.70 \pm 0.05$ and a peak energy of $\sim 257 \pm 134$ keV. After detection of GRB 240219A, long-term observations identified several candidates in optical and radio wavelengths, none of which was confirmed as the afterglow counterpart during subsequent optical and near-infrared follow-ups. The analysis of GRB 240219A classifies it as an X-ray rich GRB (XRR) with a high peak energy, presenting both challenges and opportunities for studying the physical origins of X-ray flashes, XRRs, and classical GRBs. Furthermore, linking the cutoff PL component to nonthermal synchrotron radiation suggests that the burst is driven by a Poynting flux-dominated outflow.
Comment: 15 pages, 8 figures, 3 tables |
| Document Type: |
Working Paper |
| DOI: |
10.3847/2041-8213/ad8652 |
| Access URL: |
http://arxiv.org/abs/2407.10156 |
| Accession Number: |
edsarx.2407.10156 |
| Database: |
arXiv |
