Synchrotron Radiation Dominates the Extremely Bright GRB 221009A
Abstract
The brightest Gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultra-high energy TeV photons during the prompt phase. However, analyzing the mechanism of radiation of photons in the MeV range has been difficult because the high flux causes pile-up and saturation effects in most GRB detectors. In this letter, we present systematic modeling of the time-resolved spectra of the GRB using unsaturated data obtained from Fermi/GBM (precursor) and SATech-01/GECAM-C (main emission and flare). Our approach incorporates the synchrotron radiation model, which assumes an expanding emission region with relativistic speed and a global magnetic field that decays with radius, and successfully fits such a model to the observational data. Our results indicate that the spectra of the burst are fully in accordance with a synchrotron origin from relativistic electrons accelerated at a large emission radius. The lack of thermal emission in the prompt emission spectra supports a Poynting-flux-dominated jet composition.
Keywords
Cite
@article{arxiv.2303.00898,
title = {Synchrotron Radiation Dominates the Extremely Bright GRB 221009A},
author = {Jun Yang and Xiao-Hong Zhao and Zhenyu Yan and Xiangyu I. Wang and Yan-Qiu Zhang and Zheng-Hua An and Ce Cai and Xin-Qiao Li and Zihan Li and Jia-Cong Liu and Zi-Ke Liu and Xiang Ma and Yan-Zhi Meng and Wen-Xi Peng and Rui Qiao and Lang Shao and Li-Ming Song and Wen-Jun Tan and Ping Wang and Chen-Wei Wang and Xiang-Yang Wen and Shuo Xiao and Wang-Chen Xue and Yu-han Yang and Yihan Yin and Bing Zhang and Fan Zhang and Shuai Zhang and Shuang-Nan Zhang and Chao Zheng and Shi-Jie Zheng and Shao-Lin Xiong and Bin-Bin Zhang},
journal= {arXiv preprint arXiv:2303.00898},
year = {2023}
}
Comments
12 pages, 6 figures, 2 tables. Accepted for publication in ApJL