Broadband $\gamma$-ray spectrum of supernova remnant Cassiopeia A
High Energy Astrophysical Phenomena
2025-02-10 v1
Abstract
The core-collapse supernova remnant (SNR) Cassiopeia A (Cas A) is one of the brightest galactic radio sources with an angular radius of 2.5 . Although no extension of this source has been detected in the -ray band, using more than 1000 days of LHAASO data above TeV, we find that its spectrum is significantly softer than those obtained with Imaging Air Cherenkov Telescopes (IACTs) and its flux near TeV is about two times higher. In combination with analyses of more than 16 years of \textit{Fermi}-LAT data covering , we find that the spectrum above 30 GeV deviates significantly from a single power-law, and is best described by a smoothly broken power-law with a spectral index of () below (above) a break energy of . Given differences in the angular resolution of LHAASO-WCDA and IACTs, TeV -ray emission detected with LHAASO may have a significant contribution from regions surrounding the SNR illuminated by particles accelerated earlier, which, however, are treated as background by IACTs. Detailed modelling can be used to constrain acceleration processes of TeV particles in the early stage of SNR evolution.
Cite
@article{arxiv.2502.04848,
title = {Broadband $\gamma$-ray spectrum of supernova remnant Cassiopeia A},
author = {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 A. V. Bukevich and C. M. Cai and W. Y. Cao and Zhe Cao and J. Chang and J. F. Chang and A. M. Chen and E. S. Chen and H. X. 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 Y. Chen and N. Cheng and Y. D. Cheng and M. C. Chu 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 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 C. D. 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 X. L. Guo and Y. Q. Guo and Y. Y. Guo and Y. A. 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 Y. K. Hor 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 T. Q. Huang and W. J. Huang and X. T. Huang and X. Y. Huang and Y. Huang and Y. Y. Huang 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 B. B. Li 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. Z. 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 H. D. 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 J. R. Mao and Z. Min and W. Mitthumsiri and G. B. Mou and H. J. Mu and Y. C. Nan and A. Neronov and K. C. Y. Ng and M. Y. Ni and L. Nie and L. J. Ou and P. Pattarakijwanich and Z. Y. Pei and J. C. Qi and M. Y. Qi and J. J. Qin and A. Raza and C. Y. Ren and D. Ruffolo and A. Sáiz and M. Saeed 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 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 G. W. Wang and H. G. Wang and H. H. 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. L. Xin and Y. Xing and D. R. Xiong and Z. Xiong and D. L. Xu and R. F. Xu and R. X. Xu and W. L. Xu and L. Xue and D. H. Yan and J. Z. 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 Y. H. Yao and Z. G. Yao and X. A. Ye and L. Q. Yin and N. Yin and X. H. You and Z. Y. You and Y. H. Yu and Q. Yuan and H. Yue and H. D. Zeng and T. X. Zeng and W. Zeng and M. Zha and B. B. Zhang and B. T. Zhang and F. Zhang and H. Zhang and H. M. Zhang and H. Y. Zhang and J. L. Zhang and Li Zhang and P. F. Zhang and P. P. Zhang and R. Zhang and S. R. Zhang and S. S. 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 W. J. Zhong 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},
journal= {arXiv preprint arXiv:2502.04848},
year = {2025}
}