Discovery of the Ultrahigh-energy Gamma-Ray Source LHAASO J2108+5157

作者：Z. Cao, F. Aharonian, Q. An, Axikegu, Lixin Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, Xiao-Jun Bi, Y. J. Bi, Heng Cai, J. T. Cai, Zhe Cao, J. F. Chang, J. F. Chang, B. M. Chen, E. S. Chen, J. Chen, Liang Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, Shaw H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, Na Cheng, Yaodong Cheng, S. W. Cui, Xiaohong Cui, Y. D. Cui, B. D′Ettorre Piazzoli, B. Z. Dai, H. L. Dai, Zi-Gao Dai, Dan-Zeng Dan-Zeng-Luo-Bu, D. della Volpe, X. Dong, K. K. Duan, J. H. Fan, Yi-Zhong Fan, Z. X. Fan, J. Fang, Kun Fang, C. Feng, Li Feng, S. H. Feng, Y. L. Feng, Bo Gao, C. D. Gao, L. Q. Gao, Qi Gao, Wei Gao, M. M. Ge, Li‐Sheng Geng, G. Gong, Q. B. Gou, M. H. Gu, Fulai Guo, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, Hao-Ning He, J. C. He, S. L. He, X. B. He, Y. He, Matthieu Heller, Y. K. Hor, C. Hou, H. B. Hu, S. Hu, S. C. Hu, X. Hu, D. Huang, Q. Huang, Wenhao Huang, X. T. Huang, X. Y. Huang, Zhi-Qiu Huang, Fei Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, Chao Jin, T. Ke, D. Kuleshov, K. Levochkin, Bing Li, Cheng Li, Cong Li, Li Fei, H. B. Li, Cong Li, Haiying Li, Jian Li, K. Li, Wenwen Li, X. R. Li, Xin Li, Xin Li, Yufei Li, Yuze Li, Zhe Li, Zhuo Li, En‐Wei Liang, Liang Yu, S. J. Lin, Jianwei Liu, Cheng Liu, Desheng Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, Ruo-Yu Liu, Siming Liu, Wei Liu, Y. Liu, Y. N. Liu, Zhaoyi Liu, W. J. Long, R. Lu, H. K. Lv, B. Q., L. L., Xinhua Ma, J. R. Mao, A. Masood, Z. Min, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Qi, Y. Q. Qi, Bing-Qiang Qiao, Jiajun Qin, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, Jianzheng Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Yang Su, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. Tang, W. W. Tian, B. D. Wang, C. Wang, H. G. Wang, H. G. Wang, Jincheng Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, Wei Wang, Xiang-Gao Wang, Xingjun Wang, Xiang‐Yu Wang, Yang Wang, Y. D. Wang, Yingjie Wang, Yuewu Wang, Zhongxiang Wang, Z. X. Wang, Z. Wang, Zheng Wang, Da-Ming Wei, Jun-Jie Wei, Yifan Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, Xue-Feng Wu, Shao-Qiang Xi, J. Xia, J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Hubing Xiao, G. G. Xin, Y. Xin, Yi Xing, D. L. Xu, Renxin Xu, L. Xue, Dahai Yan, J. Z. Yan, C. W. Yang, Fang Yang, J. Y. Yang, Lili Yang, Min Yang, Ruizhi Yang, S. B. Yang, Yuhua Yao, Z. G. Yao, Yunan Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Qiang Yuan, Houdun Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, Bin‐Bin Zhang, Hai-Ming Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, Lixia Zhang, Li Zhang, Lu Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, Siqi Zhang, Xiao Zhang, Xu Zhang, Y. F. Zhang, Y. L. Zhang, Yi Zhang, Yong Zhang, Bing Zhao, J. Y. Zhao, Lei Zhao, Lei Zhao, S. P. Zhao, F. Zheng, Y. G. Zheng, B. Zhou, H. Zhou, J. N. Zhou, Ping Zhou, Rong Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, Hui Zhu, K. J. Zhu, X. Zuo · 发表于：The Astrophysical Journal Letters · 年份：2021 · DOI：10.3847/2041-8213/ac2579 · 被引用次数：51 · 研究领域：Astrophysics and Cosmic Phenomena、Gamma-ray bursts and supernovae、Astrophysical Phenomena and Observations

Abstract We report the discovery of an ultrahigh-energy (UHE) gamma-ray source, LHAASO J2108+5157, by analyzing the LHAASO-KM2A data of 308.33 live days. A significant excess of gamma ray–induced showers is observed in both energy bands of 25−100 and >100 TeV with 9.5 σ and 8.5 σ , respectively. This source is not significantly favored as an extended source with an angular extension smaller than the point-spread function of KM2A. The measured energy spectrum from 20 to 200 TeV can be approximately described by a power-law function with an index of −2.83 ± 0.18 stat . A harder spectrum is demanded at lower energies considering the flux upper limit set by Fermi-LAT observations. The position of the gamma-ray emission is correlated with a giant molecular cloud, which favors a hadronic origin. No obvious counterparts have been found, and deeper multiwavelength observations will help to cast new light on this intriguing UHE source.