Cygnus X-3: A variable petaelectronvolt gamma-ray source
High Energy Astrophysical Phenomena
2026-04-14 v5
Abstract
We report the discovery of variable -rays up to petaelectronvolt from Cygnus X-3, an iconic X-ray binary. The -ray signal was detected with a statistical significance of approximately 10 by the Large High Altitude Air Shower Observatory (LHAASO). Its intrinsic spectral energy distribution (SED), extending from 0.06 to 3.7 PeV, shows a pronounced rise toward 1 PeV after accounting for absorption by the cosmic microwave background radiation. We find variability on month-long timescales at a significance of , coinciding with a high state of the GeV gamma-ray flux detected by the Fermi-LAT. This,together with a 3.2 evidence for orbital modulation, suggests that the PeV -rays originate within, or in close proximity to, the binary system itself. The observed energy spectrum and temporal modulation can be naturally explained by -ray production through photomeson processes in the innermost region of the relativistic jet, where protons need to be accelerated to tens of PeV energies.
Cite
@article{arxiv.2512.16638,
title = {Cygnus X-3: A variable petaelectronvolt gamma-ray source},
author = {The LHAASO Collaboration and Zhen Cao and F. Aharonian and Y. X. Bai and Y. W. Bao and D. Bastieri and X. J. Bi and Y. J. Bi and W. Bian and J. Blunier and A. V. Bukevich and C. M. Cai and Y. Y. Cai and W. Y. Cao and Zhe Cao and J. Chang and J. F. Chang and E. S. Chen and G. H. Chen and H. K. Chen and L. F. Chen and Liang Chen and Long Chen and M. J. Chen and M. L. Chen and Q. H. Chen and S. Chen and S. H. Chen and S. Z. Chen and T. L. Chen and X. B. Chen and X. J. Chen and X. P. Chen and Y. Chen and N. Cheng and Q. Y. Cheng and Y. D. Cheng and M. Y. Cui and S. W. Cui and X. H. Cui and Y. D. Cui and B. Z. Dai and H. L. Dai and Z. G. Dai and Danzengluobu and Y. X. Diao and A. J. Dong and X. Q. Dong and K. K. Duan and J. H. Fan and Y. Z. Fan and J. Fang and J. H. Fang and K. Fang and C. F. Feng and H. Feng and L. Feng and S. H. Feng and X. T. Feng and Y. Feng and Y. L. Feng and S. Gabici and B. Gao and Q. Gao and W. Gao and W. K. Gao and M. M. Ge and T. T. Ge and L. S. Geng and G. Giacinti and G. H. Gong and Q. B. Gou and M. H. Gu and F. L. Guo and J. Guo and K. J. Guo and X. L. Guo and Y. Q. Guo and Y. Y. Guo and R. P. Han and O. A. Hannuksela and M. Hasan and H. H. He and H. N. He and J. Y. He and X. Y. He and Y. He and S. Hernández-Cadena and B. W. Hou and C. Hou and X. Hou and H. B. Hu and S. C. Hu and C. Huang and D. H. Huang and J. J. Huang and X. L. Huang and X. T. Huang and X. Y. Huang and Y. Huang and Y. Y. Huang and A. Inventar and X. L. Ji and H. Y. Jia and K. Jia and H. B. Jiang and K. Jiang and X. W. Jiang and Z. J. Jiang and M. Jin and S. Kaci and M. M. Kang and I. Karpikov and D. Khangulyan and D. Kuleshov and K. Kurinov and Cheng Li and Cong Li and D. Li and F. Li and H. B. Li and H. C. Li and Jian Li and Jie Li and K. Li and L. Li and R. L. Li and S. D. Li and T. Y. Li and W. L. Li and X. R. Li and Xin Li and Y. Li and Zhe Li and Zhuo Li and E. W. Liang and Y. F. Liang and S. J. Lin and B. Liu and C. Liu and D. Liu and D. B. Liu and H. Liu and J. Liu and J. L. Liu and J. R. Liu and M. Y. Liu and R. Y. Liu and S. M. Liu and W. Liu and X. Liu and Y. Liu and Y. Liu and Y. N. Liu and Y. Q. Lou and Q. Luo and Y. Luo and H. K. Lv and B. Q. Ma and L. L. Ma and X. H. Ma and I. O. Maliy and J. R. Mao and Z. Min and W. Mitthumsiri and Y. Mizuno and G. B. Mou and A. Neronov and K. C. Y. Ng and M. Y. Ni and L. Nie and L. J. Ou and Z. W. Ou and P. Pattarakijwanich and Z. Y. Pei and D. Y. Peng and J. C. Qi and M. Y. Qi and J. J. Qin and D. Qu and A. Raza and C. Y. Ren and D. Ruffolo and A. Sáiz and D. Savchenko and D. Semikoz and L. Shao and O. Shchegolev and Y. Z. Shen and X. D. Sheng and Z. D. Shi and F. W. Shu and H. C. Song and Yu. V. Stenkin and V. Stepanov and Y. Su and D. X. Sun and H. Sun and J. X. Sun and Q. N. Sun and X. N. Sun and Z. B. Sun and N. H. Tabasam and J. Takata and P. H. T. Tam and H. B. Tan and Q. W. Tang and R. Tang and Z. B. Tang and W. W. Tian and C. N. Tong and L. H. Wan and C. Wang and D. H. Wang and G. W. Wang and H. G. Wang and J. C. Wang and K. Wang and Kai Wang and Kai Wang and L. P. Wang and L. Y. Wang and L. Y. Wang and R. Wang and W. Wang and X. G. Wang and X. J. Wang and X. Y. Wang and Y. Wang and Y. D. Wang and Z. H. Wang and Z. X. Wang and Zheng Wang and D. M. Wei and J. J. Wei and Y. J. Wei and T. Wen and S. S. Weng and C. Y. Wu and H. R. Wu and Q. W. Wu and S. Wu and X. F. Wu and Y. S. Wu and S. Q. Xi and J. Xia and J. J. Xia and G. M. Xiang and D. X. Xiao and G. Xiao and Y. F. Xiao and Y. L. Xin and H. D. Xing and Y. Xing and D. R. Xiong and B. N. Xu and C. Y. Xu and D. L. Xu and R. F. Xu and R. X. Xu and S. S. Xu and W. L. Xu and L. Xue and D. H. Yan and T. Yan and C. W. Yang and C. Y. Yang and F. F. Yang and L. L. Yang and M. J. Yang and R. Z. Yang and W. X. Yang and Z. H. Yang and Z. G. Yao and X. A. Ye and L. Q. Yin and N. Yin and X. H. You and Z. Y. You and Q. Yuan and H. Yue and H. D. Zeng and T. X. Zeng and W. Zeng and X. T. Zeng and M. Zha and B. B. Zhang and B. T. Zhang and C. Zhang and H. Zhang and H. M. Zhang and H. Y. Zhang and J. L. Zhang and J. Y. Zhang and Li Zhang and P. F. Zhang and R. Zhang and S. R. Zhang and S. S. Zhang and S. Y. Zhang and W. Zhang and W. Y. Zhang and X. Zhang and X. P. Zhang and Yi Zhang and Yong Zhang and Z. P. Zhang and J. Zhao and L. Zhao and L. Z. Zhao and S. P. Zhao and X. H. Zhao and Z. H. Zhao and F. Zheng and T. C. Zheng and B. Zhou and H. Zhou and J. N. Zhou and M. Zhou and P. Zhou and R. Zhou and X. X. Zhou and X. X. Zhou and B. Y. Zhu and C. G. Zhu and F. R. Zhu and H. Zhu and K. J. Zhu and Y. C. Zou and X. Zuo and J. S. Wang},
journal= {arXiv preprint arXiv:2512.16638},
year = {2026}
}
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