<p>We report a dedicated study of the newly discovered extended UHE <i>γ</i>-ray source 1LHAASO J0056+6346u. Analyzing 979 d of LHAASO-WCDA data and 1389 d of LHAASO-KM2A data, we observed a significant excess of <i>γ</i>-ray events with both WCDA and KM2A. Assuming a point power-law source with a fixed spectral index, the significance maps reveal excesses of 12.65 <i>σ</i>, 22.18 <i>σ</i>, and 10.24 <i>σ</i> in the energy ranges of 1–25, 25–100, and &gt;100 TeV, respectively. We use a 3D likelihood algorithm to derive the morphological and spectral parameters, and the source is detected with significances of 13.72 <i>σ</i> by WCDA and 25.27 <i>σ</i> by KM2A. The best-fit positions derived from WCDA and KM2A data are (R.A. = 13.96° ± 0.09°, Decl. = 63.92° ± 0.05°) and (R.A. = 14.00° ± 0.05°, Decl. = 63.79° ± 0.02°), respectively. The angular size (<i>r</i><sub>39</sub>) of 1LHAASO J0056+6346u is 0.34° ± 0.04° at 1–25 TeV and 0.24° ± 0.02° at &gt;25 TeV. The differential flux of this UHE <i>γ</i>-ray source can be described by an exponential cutoff power-law function: (2.67 ± 0.25) × 10<sup>−15</sup> (<i>E</i>/20 TeV)<sup>(−1.97±0.10)</sup> e<sup>−<i>E</i>/(55.1±7.2) TeV</sup> TeV<sup>−1</sup> cm<sup>−2</sup> s<sup>−1</sup>. To explore potential sources of <i>γ</i>-ray emission, we investigated the gas distribution around 1LHAASO J0056+6346u. 1LHAASO J0056+6346u is likely to be a TeV PWN powered by an unknown pulsar, which would naturally explain both its spatial and spectral properties. Another explanation is that this UHE <i>γ</i>-ray source might be associated with gas content illuminated by a nearby CR accelerator, possibly the SNR candidate G124.0+1.4.</p>

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Study of ultra-high-energy gamma-ray source 1LHAASO J0056+6346u and its possible origins

  • Zhen Cao,
  • F. Aharonian,
  • Axikegu,
  • Y. X. Bai,
  • Y. W. Bao,
  • D. Bastieri,
  • X. J. Bi,
  • Y. J. Bi,
  • W. Bian,
  • A. V. Bukevich,
  • Q. Cao,
  • W. Y. Cao,
  • Zhe Cao,
  • J. Chang,
  • J. F. Chang,
  • A. M. Chen,
  • E. S. Chen,
  • H. X. Chen,
  • Liang Chen,
  • Lin Chen,
  • Long Chen,
  • M. J. Chen,
  • M. L. Chen,
  • Q. H. Chen,
  • S. Chen,
  • S. H. Chen,
  • S. Z. Chen,
  • T. L. Chen,
  • Y. Chen,
  • N. Cheng,
  • Y. D. Cheng,
  • M. C. Chu,
  • M. Y. Cui,
  • S. W. Cui,
  • X. H. Cui,
  • Y. D. Cui,
  • B. Z. Dai,
  • H. L. Dai,
  • Z. G. Dai,
  • Danzengluobu,
  • X. Q. Dong,
  • K. K. Duan,
  • J. H. Fan,
  • Y. Z. Fan,
  • J. Fang,
  • J. H. Fang,
  • K. Fang,
  • C. F. Feng,
  • H. Feng,
  • L. Feng,
  • S. H. Feng,
  • X. T. Feng,
  • Y. Feng,
  • Y. L. Feng,
  • S. Gabici,
  • B. Gao,
  • C. D. Gao,
  • Q. Gao,
  • W. Gao,
  • W. K. Gao,
  • M. M. Ge,
  • T. T. Ge,
  • L. S. Geng,
  • G. Giacinti,
  • G. H. Gong,
  • Q. B. Gou,
  • M. H. Gu,
  • F. L. Guo,
  • J. Guo,
  • X. L. Guo,
  • Y. Q. Guo,
  • Y. Y. Guo,
  • Y. A. Han,
  • O. A. Hannuksela,
  • M. Hasan,
  • H. H. He,
  • H. N. He,
  • J. Y. He,
  • Y. He,
  • Y. K. Hor,
  • B. W. Hou,
  • C. Hou,
  • X. Hou,
  • H. B. Hu,
  • Q. Hu,
  • S. C. Hu,
  • C. Huang,
  • D. H. Huang,
  • T. Q. Huang,
  • W. J. Huang,
  • X. T. Huang,
  • X. Y. Huang,
  • Y. Huang,
  • Y. Y. Huang,
  • X. L. Ji,
  • H. Y. Jia,
  • K. Jia,
  • H. B. Jiang,
  • K. Jiang,
  • X. W. Jiang,
  • Z. J. Jiang,
  • M. Jin,
  • M. M. Kang,
  • I. Karpikov,
  • D. Khangulyan,
  • D. Kuleshov,
  • K. Kurinov,
  • B. B. Li,
  • C. M. Li,
  • Cheng Li,
  • Cong Li,
  • D. Li,
  • F. Li,
  • H. B. Li,
  • H. C. Li,
  • Jian Li,
  • Jie Li,
  • K. Li,
  • S. D. Li,
  • W. L. Li,
  • W. L. Li,
  • X. R. Li,
  • Xin Li,
  • Y. Z. Li,
  • Zhe Li,
  • Zhuo Li,
  • E. W. Liang,
  • Y. F. Liang,
  • S. J. Lin,
  • B. Liu,
  • C. Liu,
  • D. Liu,
  • D. B. Liu,
  • H. Liu,
  • H. D. Liu,
  • J. Liu,
  • J. L. Liu,
  • M. Y. Liu,
  • R. Y. Liu,
  • S. M. Liu,
  • W. Liu,
  • Y. Liu,
  • Y. N. Liu,
  • Q. Luo,
  • Y. Luo,
  • H. K. Lv,
  • B. Q. Ma,
  • L. L. Ma,
  • X. H. Ma,
  • J. R. Mao,
  • Z. Min,
  • W. Mitthumsiri,
  • H. J. Mu,
  • Y. C. Nan,
  • A. Neronov,
  • K. C. Y. Ng,
  • L. J. Ou,
  • P. Pattarakijwanich,
  • Z. Y. Pei,
  • J. C. Qi,
  • M. Y. Qi,
  • B. Q. Qiao,
  • J. J. Qin,
  • A. Raza,
  • D. Ruffolo,
  • A. Sáiz,
  • M. Saeed,
  • D. Semikoz,
  • L. Shao,
  • O. Shchegolev,
  • X. D. Sheng,
  • F. W. Shu,
  • H. C. Song,
  • Yu.V. Stenkin,
  • V. Stepanov,
  • Y. Su,
  • D. X. Sun,
  • Q. N. Sun,
  • X. N. Sun,
  • Z. B. Sun,
  • J. Takata,
  • P. H. T. Tam,
  • Q. W. Tang,
  • R. Tang,
  • Z. B. Tang,
  • W. W. Tian,
  • L. H. Wan,
  • C. Wang,
  • C. B. Wang,
  • G. W. Wang,
  • H. G. Wang,
  • H. H. Wang,
  • J. C. Wang,
  • Kai Wang,
  • Kai Wang,
  • L. P. Wang,
  • L. Y. Wang,
  • P. H. Wang,
  • R. Wang,
  • W. Wang,
  • X. G. Wang,
  • X. Y. Wang,
  • Y. Wang,
  • Y. D. Wang,
  • Y. J. Wang,
  • Z. H. Wang,
  • Z. X. Wang,
  • Zhen Wang,
  • Zheng Wang,
  • D. M. Wei,
  • J. J. Wei,
  • Y. J. Wei,
  • T. Wen,
  • C. Y. Wu,
  • H. R. Wu,
  • Q. W. Wu,
  • S. Wu,
  • X. F. Wu,
  • Y. S. Wu,
  • S. Q. Xi,
  • J. Xia,
  • G. M. Xiang,
  • D. X. Xiao,
  • G. Xiao,
  • Y. L. Xin,
  • Y. Xing,
  • D. R. Xiong,
  • Z. Xiong,
  • D. L. Xu,
  • R. F. Xu,
  • R. X. Xu,
  • W. L. Xu,
  • L. Xue,
  • D. H. Yan,
  • J. Z. Yan,
  • T. Yan,
  • C. W. Yang,
  • C. Y. Yang,
  • F. Yang,
  • F. F. Yang,
  • L. L. Yang,
  • M. J. Yang,
  • R. Z. Yang,
  • W. X. Yang,
  • Y. H. Yao,
  • Z. G. Yao,
  • L. Q. Yin,
  • N. Yin,
  • X. H. You,
  • Z. Y. You,
  • Y. H. Yu,
  • Q. Yuan,
  • H. Yue,
  • H. D. Zeng,
  • T. X. Zeng,
  • W. Zeng,
  • M. Zha,
  • B. B. Zhang,
  • F. Zhang,
  • H. Zhang,
  • H. M. Zhang,
  • H. Y. Zhang,
  • J. L. Zhang,
  • Li Zhang,
  • P. F. Zhang,
  • P. P. Zhang,
  • R. Zhang,
  • S. B. Zhang,
  • S. R. Zhang,
  • S. S. Zhang,
  • X. Zhang,
  • X. P. Zhang,
  • Y. F. Zhang,
  • Yi Zhang,
  • Yong Zhang,
  • B. Zhao,
  • J. Zhao,
  • L. Zhao,
  • L. Z. Zhao,
  • S. P. Zhao,
  • X. H. Zhao,
  • F. Zheng,
  • W. J. Zhong,
  • B. Zhou,
  • H. Zhou,
  • J. N. Zhou,
  • M. Zhou,
  • P. Zhou,
  • R. Zhou,
  • X. X. Zhou,
  • X. X. Zhou,
  • B. Y. Zhu,
  • C. G. Zhu,
  • F. R. Zhu,
  • H. Zhu,
  • K. J. Zhu,
  • Y. C. Zou,
  • X. Zuo

摘要

We report a dedicated study of the newly discovered extended UHE γ-ray source 1LHAASO J0056+6346u. Analyzing 979 d of LHAASO-WCDA data and 1389 d of LHAASO-KM2A data, we observed a significant excess of γ-ray events with both WCDA and KM2A. Assuming a point power-law source with a fixed spectral index, the significance maps reveal excesses of 12.65 σ, 22.18 σ, and 10.24 σ in the energy ranges of 1–25, 25–100, and >100 TeV, respectively. We use a 3D likelihood algorithm to derive the morphological and spectral parameters, and the source is detected with significances of 13.72 σ by WCDA and 25.27 σ by KM2A. The best-fit positions derived from WCDA and KM2A data are (R.A. = 13.96° ± 0.09°, Decl. = 63.92° ± 0.05°) and (R.A. = 14.00° ± 0.05°, Decl. = 63.79° ± 0.02°), respectively. The angular size (r39) of 1LHAASO J0056+6346u is 0.34° ± 0.04° at 1–25 TeV and 0.24° ± 0.02° at >25 TeV. The differential flux of this UHE γ-ray source can be described by an exponential cutoff power-law function: (2.67 ± 0.25) × 10−15 (E/20 TeV)(−1.97±0.10) eE/(55.1±7.2) TeV TeV−1 cm−2 s−1. To explore potential sources of γ-ray emission, we investigated the gas distribution around 1LHAASO J0056+6346u. 1LHAASO J0056+6346u is likely to be a TeV PWN powered by an unknown pulsar, which would naturally explain both its spatial and spectral properties. Another explanation is that this UHE γ-ray source might be associated with gas content illuminated by a nearby CR accelerator, possibly the SNR candidate G124.0+1.4.