Author: "D, Ruffolo" - Searchworks@Jio Institute Digital Library Search Results

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73 results on '"D, Ruffolo"'

1. An Enigmatic PeVatron in an Area around H ii Region G35.6−0.5

Author: 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, B. Q. 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, 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, 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, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo, and (The LHAASO Collaboration)
Subjects: Gamma-rays, Gamma-ray sources, H II regions, Supernova remnants, Astrophysics, QB460-466
Abstract: Identifying Galactic PeVatrons (PeV particle accelerators) from ultrahigh-energy (UHE, >100 TeV) γ -ray sources plays a crucial role in revealing the origin of Galactic cosmic rays. The UHE source 1LHAASO J1857+0203u is suggested to be associated with HESS J1858+020, which may be attributed to the possible PeVatron candidate supernova remnant (SNR) G35.6−0.4 or H ii region G35.6−0.5. We perform detailed analysis on the very-high-energy and UHE γ -ray emissions toward this region with data from the Large High Altitude Air Shower Observatory (LHAASO). 1LHAASO J1857+0203u is detected with a significance of 11.6 σ above 100 TeV, indicating the presence of a PeVatron. It has an extent of ∼0 $\mathop{.}\limits^{\unicode{x000B0}}$ 18 with a power-law (PL) spectral index of ∼2.5 at 1–25 TeV and pointlike emission with a PL spectral index of ∼3.2 above 25 TeV. Using archival CO and H i data, we identify some molecular and atomic clouds that may be associated with the TeV γ -ray emissions. Our modeling indicates that the TeV γ -ray emissions are unlikely to arise from clouds illuminated by the protons that escaped from SNR G35.6−0.4. In the scenario in which H ii region G35.6−0.5 could accelerate particles to the UHE band, the observed GeV–TeV γ -ray emission could be well explained by a hadronic model with a PL spectral index of ∼2.0 and cutoff energy of ∼450 TeV. However, an origin in an evolved pulsar wind nebula cannot be ruled out.
Published: 2025
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2. Discovery of Very High Energy Gamma-Ray Emissions from the Low-luminosity AGN NGC 4278 by LHAASO

Author: 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. 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, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, 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, D. H. Huang, T. Q. Huang, W. J. Huang, X. T. Huang, X. Y. Huang, Y. Huang, X. L. Ji, H. Y. Jia, K. Jia, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, M. M. Kang, I. Karpikov, 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, 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, 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, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. 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, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo, and The LHAASO Collaboration
Subjects: High energy astrophysics, Gamma-ray astronomy, Low-luminosity active galactic nuclei, LINER galaxies, Blazars, Fanaroff-Riley radio galaxies, Astrophysics, QB460-466
Abstract: The first source catalog of the Large High Altitude Air Shower Observatory (LHAASO) reported the detection of a very high energy gamma-ray source, 1LHAASO J1219+2915. This Letter presents a further detailed study of the spectral and temporal behavior of this pointlike source. The best-fit position of the TeV source (R.A. = 185.°05 ± 0.°04, decl. = 29.°25 ± 0.°03) is compatible with NGC 4278 within ∼0.°03. Variation analysis shows an indication of variability on a timescale of a few months in the TeV band, which is consistent with low-frequency observations. Based on these observations, we report the detection of TeV γ -ray emissions from this low-luminosity active galactic nucleus. The observation by LHAASO's Water Cherenkov Detector Array during the active period has a significance level of 8.8 σ with a best-fit photon spectral index Γ = 2.56 ± 0.14 and a flux f _1–10 TeV = (7.0 ± 1.1 _sta ± 0.35 _syst ) × 10 ^−13 photons cm ^−2 s ^−1 , or approximately 5% of the Crab Nebula. The discovery of VHE gamma-ray emission from NGC 4278 indicates that compact, weak radio jets can efficiently accelerate particles and emit TeV photons.
Published: 2024
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3. Detection of Very High-energy Gamma-Ray Emission from the Radio Galaxy M87 with LHAASO

Author: 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, 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, 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, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, and X. Zuo
Subjects: Active galactic nuclei, High energy astrophysics, Astrophysics, QB460-466
Abstract: The nearby radio galaxy M87 is a very high-energy (VHE) gamma-ray emitter established by observations with ground-based gamma-ray detectors. Here we report the long-term monitoring of M87 from 2021 to 2024 with the Large High Altitude Air Shower Observatory (LHAASO). M87 has been detected by LHAASO with a statistical significance ∼ 9 σ . The observed energy spectrum extends to 20 TeV, with a possible hardening at ∼20 TeV and then a clear softening at higher energies. Assuming that the intrinsic spectrum is described by a single power law up to 20 TeV, a tight upper bound on the extragalactic background light intensity is obtained. A strong VHE flare lasting 8 days, with a rise time of ${\tau }_{r}^{\mathrm{rise}}=1.05\pm 0.49$ days and decay time of ${\tau }_{d}^{\mathrm{decay}}=2.17\pm 0.58$ days, was found in early 2022. A possible GeV flare is seen also in Fermi Large Area Telescope data during the VHE flare period. The variability time as short as 1 day seen in the LHAASO data suggests a compact emission region with a size of ∼3 × 10 ^15 δ cm ( δ being the Doppler factor of the emitting region), corresponding to a few Schwarzschild radii of the central supermassive black hole in M87. The continuous monitoring of the source reveals a duty cycle of ∼1% for VHE flares with a flux above 10 ^−11 erg cm ^−2 s ^−1 .
Published: 2024
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4. The First LHAASO Catalog of Gamma-Ray Sources

Author: Zhen Cao, F. Aharonian, Q. An, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, J. T. Cai, Q. Cao, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, E. S. Chen, Liang Chen, Lin Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, M. Y. Cui, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, D. della Volpe, X. Q. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, X. T. Feng, Y. L. Feng, S. Gabici, B. Gao, C. D. Gao, L. Q. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. Y. He, X. B. He, Y. He, M. Heller, Y. K. Hor, B. W. Hou, C. Hou, X. Hou, H. B. Hu, Q. Hu, S. C. Hu, D. H. Huang, T. Q. Huang, W. J. Huang, X. T. Huang, X. Y. Huang, Y. Huang, Z. C. Huang, X. L. Ji, H. Y. Jia, K. Jia, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, M. M. Kang, T. Ke, D. Kuleshov, K. Kurinov, B. B. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, Jian Li, Jie Li, K. 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, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, R. Lu, Q. 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, Z. W. Ou, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, Y. Q. Qi, B. Q. Qiao, J. J. Qin, D. Ruffolo, A. Sáiz, D. Semikoz, C. Y. Shao, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Q. W. Tang, Z. B. Tang, W. W. Tian, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, K. 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, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, 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, F. Yang, F. F. Yang, H. W. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, 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. M. Zhang, H. Y. Zhang, J. L. Zhang, L. X. 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, F. Zheng, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, X. Zuo, and (The LHAASO Collaboration)
Subjects: Gamma-ray astronomy, Gamma-ray observatories, Catalogs, Astrophysics, QB460-466
Abstract: We present the first catalog of very-high-energy and ultra-high-energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory. The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array from 2021 March to 2022 September and 933 days of data recorded by the Kilometer Squared Array from 2020 January to 2022 September. This catalog represents the main result from the most sensitive large coverage gamma-ray survey of the sky above 1 TeV, covering decl. from −20° to 80°. In total, the catalog contains 90 sources with an extended size smaller than 2° and a significance of detection at >5 σ . Based on our source association criteria, 32 new TeV sources are proposed in this study. Among the 90 sources, 43 sources are detected with ultra-high energy ( E > 100 TeV) emission at >4 σ significance level. We provide the position, extension, and spectral characteristics of all the sources in this catalog.
Published: 2024
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5. A Detailed Survey of the Parallel Mean Free Path of Solar Energetic Particle Protons and Electrons

Author: J. T. Lang, R. D. Strauss, N. E. Engelbrecht, J. P. van den Berg, N. Dresing, D. Ruffolo, and R. Bandyopadhyay
Subjects: Cosmic rays, Heliosphere, Solar wind, Interplanetary turbulence, Solar energetic particles, Astrophysics, QB460-466
Abstract: In this work, more than a dozen solar energetic particle (SEP) events are identified where the source region is magnetically well connected to at least one spacecraft at 1 au. The observed intensity–time profiles, for all available proton and electron energy channels, are compared to results computed using a numerical one-dimensional SEP transport model in order to derive the parallel mean free paths (pMFPs) as a function of energy (or rigidity) at 1 au. These inversion results are then compared to theoretical estimates of the pMFP, using observed turbulence quantities with observationally motivated variations as input. For protons, a very good comparison between inversion and theoretical results is obtained. It is shown that the observed inter-event variations in the inversion pMFP values can be explained by natural variations in the background turbulence values. For electrons, there is relatively good agreement with pMFPs derived assuming the damping model of dynamical turbulence, although the theoretical values are extremely sensitive to the details of the turbulence dissipation range, which themselves display a high level of variation.
Published: 2024
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6. Cosmic-Ray Flux Correlation between MCMU and JBGO Neutron Monitors

Author: A. Kittiya, W. Nuntiyakul, A. Seripienlert, S. Madlee, W. Sonsrettee, P. Evenson, D. Ruffolo, A. Sáiz, S. Oh, J. Jung, Q. Q. Shi, S. Wang, C. Y. Han, L. M. Zhai, and K. Munakata
Subjects: Cosmic anisotropy, Cosmic ray detectors, Forbush effect, Galactic cosmic rays, Astrophysics, QB460-466
Abstract: Neutron monitors (NMs) are large ground-based detectors of atmospheric secondary particles, mostly neutrons, from primary cosmic rays. Their sky direction and rigidity imply a well-defined incoming (asymptotic) direction in space. From 2015 December 16 to 2017 January 8, 6 of the 18 NM counters had been transferred from McMurdo to Jang Bogo, both in Antarctica, so data from similar detectors were recorded simultaneously at these two nearby NM stations. Autocorrelations of these NM count rates are well fit as the sum of three components: an exponential function and a cosine with a period of 1 day, both centered at zero lag, plus a constant. Fitting the cross correlation of the two count rates, the functions are no longer centered at zero lag. The best-fit cosine phase is at time lag −160.22 ± 0.12 minutes. Calculating cosmic-ray trajectories in Earth's magnetic field throughout the time interval, the mean difference in response-weighted asymptotic longitudes corresponds to time lag −169.41 ± 0.31 minutes, in close agreement with the observed lag. Thus, the cosine term is consistent with and provides a technique to cleanly measure the cosmic-ray anisotropy. In contrast, the peak term shows a time lag of –14.55 minutes, much closer to the –9.60 minutes lag in rotation due to the difference in geographic longitude. We find a similar behavior in the correlations between other pairs of stations. We propose that rapid fluctuations in the counting rate may be primarily due to cosmic-ray particles of very high energy.
Published: 2024
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7. Construction and on-site performance of the LHAASO WFCTA camera

Author: F. Aharonian, Q. An, Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, X. Zuo, and The LHAASO Collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here.
Published: 2021
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8. Solar Magnetic Polarity Effect on Neutron Monitor Count Rates: Comparing Latitude Surveys and Antarctic Stations

Author: K. Poopakun, W. Nuntiyakul, S. Khamphakdee, A. Seripienlert, D. Ruffolo, P. Evenson, P. Jiang, P. Chuanraksasat, K. Munakata, M. L. Duldig, J. E. Humble, J. Madsen, B. Soonthornthum, and S. Komonjinda
Subjects: Galactic cosmic rays, Solar cycle, Solar-terrestrial interactions, Astrophysics, QB460-466
Abstract: The Galactic cosmic-ray spectrum manifests pronounced variations over the 11 yr sunspot cycle and more subtle variations over the 22 yr solar magnetic cycle. An important tool to study these variations is repeated latitude surveys with neutron monitors (NMs) on board icebreakers in conjunction with land-based references. We revisit 13 annual latitude surveys from 1994 to 2007 using reference data from the Mawson NM instead of McMurdo NM (which closed in 2017). We then consider two more latitude surveys (2018 and 2019) with a monitor similar to the 3NM64 in the previous surveys but without lead rings around the central tube, a so-called “semi-leaded neutron monitor.” The new surveys extend the linear relationship among data taken at different cutoff rigidity ranges. They also confirm the “crossover” measured near solar minima during epochs of opposite solar magnetic polarity and the absence of a crossover for epochs having the same solar magnetic polarity.
Published: 2023
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9. Energetic Particle Perpendicular Diffusion: Simulations and Theory in Noisy Reduced Magnetohydrodynamic Turbulence

Author: A. P. Snodin, T. Jitsuk, D. Ruffolo, and W. H. Matthaeus
Published: 2022
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10. A dynamic range extension system for LHAASO WCDA-1

Author: F. Aharonian, Q. An, null Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, null Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Y. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, and X. Zuo
Subjects: Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Dynamic range, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic ray, Extension (predicate logic), Measure (mathematics), Effective nuclear charge, Nuclear physics, Air shower, Nuclear Energy and Engineering, Orders of magnitude (time), Energy (signal processing)
Abstract: The main scientific goal of LHAASO-WCDA is to survey gamma-ray sources with energy from 100 GeV to 30 TeV. To observe high-energy shower events, especially to measure the energy spectrum of cosmic rays from 100 TeV to 10 PeV, a dynamic range extension system (WCDA++) is designed to use a 1.5-inch PMT with a dynamic range of four orders of magnitude for each cell in WCDA-1. The dynamic range is extended by using these PMTs to measure the effective charge density in the core region of air shower events, which is an important parameter for identifying the composition of primary particles. The system has been running for more than one year. In this paper, the details of the design and performance of WCDA++ are presented.
Published: 2021
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11. Constraints on heavy decaying dark matter from 570 days of LHAASO observations

Author: Zhen, Cao, F, Aharonian, Q, An, Axikegu, L X, Bai, Y X, Bai, Y W, Bao, D, Bastieri, X J, Bi, Y J, Bi, J T, Cai, Zhe, Cao, J, Chang, J F, Chang, E S, Chen, Liang, Chen, Long, Chen, M J, Chen, M L, Chen, Q H, Chen, S H, Chen, S Z, Chen, T L, Chen, Y, Chen, H L, Cheng, N, Cheng, Y D, Cheng, S W, Cui, X H, Cui, Y D, Cui, B, D'Ettorre Piazzoli, B Z, Dai, H L, Dai, Z G, Dai, Danzengluobu, D, Della Volpe, K K, Duan, J H, Fan, Y Z, Fan, Z X, Fan, J, Fang, K, Fang, C F, Feng, L, Feng, S H, Feng, X T, Feng, Y L, Feng, B, Gao, C D, Gao, L Q, Gao, Q, Gao, W, Gao, W K, Gao, M M, Ge, L S, Geng, G H, Gong, Q B, Gou, M H, Gu, F L, Guo, J G, Guo, X L, Guo, Y Q, Guo, Y Y, Guo, Y A, Han, H H, He, H N, He, S L, He, X B, He, Y, He, M, Heller, Y K, Hor, C, Hou, X, Hou, H B, Hu, Q, Hu, S, Hu, S C, Hu, X J, Hu, D H, Huang, W H, Huang, X T, Huang, X Y, Huang, Y, Huang, Z C, Huang, X L, Ji, H Y, Jia, K, Jia, K, Jiang, Z J, Jiang, M, Jin, M M, Kang, T, Ke, D, Kuleshov, K, Levochkin, B B, Li, Cheng, Li, Cong, Li, F, Li, H B, Li, H C, Li, H Y, Li, J, Li, Jian, Li, Jie, Li, K, 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, H, Liu, H D, Liu, J, Liu, J L, Liu, J S, Liu, J Y, Liu, M Y, Liu, R Y, Liu, S M, Liu, W, Liu, Y, Liu, Y N, Liu, W J, Long, R, Lu, Q, Luo, H K, Lv, B Q, Ma, L L, Ma, X H, Ma, J R, Mao, A, Masood, Z, Min, W, Mitthumsiri, Y C, Nan, Z W, Ou, B Y, Pang, P, Pattarakijwanich, Z Y, Pei, M Y, Qi, Y Q, Qi, B Q, Qiao, J J, Qin, D, Ruffolo, A, Sáiz, C Y, Shao, L, Shao, O, Shchegolev, X D, Sheng, J Y, Shi, H C, Song, Yu V, Stenkin, V, Stepanov, Y, Su, Q N, Sun, X N, Sun, Z B, Sun, P H T, Tam, Z B, Tang, W W, Tian, B D, Wang, C, Wang, H, Wang, H G, Wang, J C, Wang, J S, Wang, L P, Wang, L Y, Wang, R, Wang, R N, Wang, W, Wang, X G, Wang, X Y, Wang, Y, Wang, Y D, Wang, Y J, Wang, Y P, 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, S, Wu, X F, Wu, Y S, Wu, S Q, Xi, J, Xia, J J, Xia, G M, Xiang, D X, Xiao, G, Xiao, G G, Xin, Y L, Xin, Y, Xing, Z, Xiong, D L, Xu, R X, Xu, L, Xue, D H, Yan, J Z, Yan, C W, Yang, F F, Yang, H W, Yang, J Y, Yang, L L, Yang, M J, Yang, R Z, Yang, S B, Yang, Y H, Yao, Z G, Yao, Y M, Ye, 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, Z K, Zeng, M, Zha, X X, Zhai, B B, Zhang, F, Zhang, H M, Zhang, H Y, Zhang, J L, Zhang, L X, Zhang, Li, Zhang, Lu, 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, Y L, Zhang, Yi, Zhang, Yong, Zhang, B, Zhao, J, Zhao, L, Zhao, L Z, Zhao, S P, Zhao, F, Zheng, Y, Zheng, B, Zhou, H, Zhou, J N, Zhou, P, Zhou, R, Zhou, X X, Zhou, C G, Zhu, F R, Zhu, H, Zhu, K J, Zhu, X, Zuo, S, Ando, M, Chianese, D F G, Fiorillo, G, Miele, K C Y, Ng, and GRAPPA (ITFA, IoP, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), General Physics and Astronomy, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 105 and 109 GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.
Published: 2022

12. Large amplitude bidirectional anisotropy of cosmic-ray intensity observed with world-wide networks of ground-based neutron monitors and muon detectors in November, 2021

Author: K. Munakata, M. Kozai, C. Kato, Y. Hayashi, R. Kataoka, A. Kadokura, M. Tokumaru, R. R. S. Mendonça, E. Echer, A. Dal Lago, M. Rockenbach, N. J. Schuch, J. V. Bageston, C. R. Braga, H. K. Al Jassar, M. M. Sharma, M. L. Duldig, J. E. Humble, I. Sabbah, P. Evenson, P.-S. Mangeard, T. Kuwabara, D. Ruffolo, A. Sáiz, W. Mitthumsiri, W. Nuntiyakul, and J. Kóta
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: We analyze the cosmic-ray variations during a significant Forbush decrease observed with world-wide networks of ground-based neutron monitors and muon detectors during November 3-5, 2021. Utilizing the difference between primary cosmic-ray rigidities monitored by neutron monitors and muon detectors, we deduce the rigidity spectra of the cosmic-ray density (or omnidirectional intensity) and the first- and second-order anisotropies separately, for each hour of data. A clear two-step decrease is seen in the cosmic-ray density with the first $\sim2\%$ decrease after the interplanetary shock arrival followed by the second $\sim5\%$ decrease inside the magnetic flux rope (MFR) at 15 GV. Most strikingly, a large bidirectional streaming along the magnetic field is observed in the MFR with a peak amplitude of $\sim5\%$ at 15 GV which is comparable to the total density decrease inside the MFR. The bidirectional streaming could be explained by adiabatic deceleration and/or focusing in the expanding MFR, which have stronger effects for pitch angles near 90$^\circ$, or by selective entry of GCRs along a leg of the MFR. The peak anisotropy and density depression in the flux rope both decrease with increasing rigidity. The spectra vary dynamically indicating that the temporal variations of density and anisotropy appear different in neutron monitor and muon detector data., Accepted for publication in the Astrophysical Journal
Published: 2022

13. Design and Testing of the Front-End Electronics of WCDA in LHAASO

Author: F. Aharonian, Q. An, null Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, null Danzengluobu, R.S. Dong, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, J.L. Gu, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, Z.Q. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B.B. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, B.D. Piazzoli, M.Y. Qi, J.J. Qin, D. Ruffolo, V. Rulev, A. Saiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, C.X. Song, H.C. Song, Yu. V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H.T. Tam, Z.B. Tang, W.W. Tian, D. della Volpe, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, X.B. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, S.Z. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, and X. Zuo
Subjects: Nuclear and High Energy Physics, Photomultiplier, Dynamic range, Cherenkov detector, Detector, law.invention, Root mean square, Air shower, Nuclear Energy and Engineering, Observatory, law, Environmental science, Electronics, Electrical and Electronic Engineering, Remote sensing
Abstract: Water Cherenkov detector array (WCDA) is one of the key parts of the Large High Altitude Air Shower Observatory (LHAASO), the construction of which was completed by the end of 2020. The WCDA covers a 78 000-m2 area and there exist 3120 large size photomultiplier tubes (PMTs) in three ponds: 8-in PMTs are used in WCDA pond No. 1 and 20-in PMTs are used in ponds No. 2 and No. 3. The front-end electronics (FEE) system based on multigain measurement technique is designed to achieve both high-precision time and charge measurements over a large dynamic range from single photon electron (S.P.E.) to 4000 P.E. (for water pond No. 1)/1800 P.E. (for water ponds No. 2 and No. 3). To achieve a high-quality clock distribution and phase alignment as well as mixed transmission of data, clock, and commands in one fiber over a long distance, an enhanced white rabbit (WR) technique is used. Testing of all the 350 FEE modules for the WCDA is presented in this article. Test results indicate that the charge resolution is better than 20% at S.P.E. and 1% at 1800/4000 P.E. and the time resolution is better than 300 ps root mean square (rms), which successfully meets the application requirement. All the FEE modules have been fabricated and installed for the LHAASO WCDA from 2018 to 2020, and the initial commissioning operation indicates that the FEEs function well.
Published: 2021
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14. Measures of Scale-dependent Alfvénicity in the First PSP Solar Encounter

Author: T. N. Parashar, M. L. Goldstein, B. A. Maruca, W. H. Matthaeus, D. Ruffolo, R. Bandyopadhyay, R. Chhiber, A. Chasapis, R. Qudsi, D. Vech, D. A. Roberts, S. D. Bale, J. W. Bonnell, T. Dudok de Wit, K. Goetz, P. R. Harvey, R. J. MacDowall, D. Malaspina, M. Pulupa, J. C. Kasper, K. E. Korreck, A. W. Case, M. Stevens, P. Whittlesey, D. Larson, R. Livi, M. Velli, and N. Raouafi
Published: 2020
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15. Observations of Energetic-particle Population Enhancements along Intermittent Structures near the Sun from the Parker Solar Probe

Author: Riddhi Bandyopadhyay, W. H. Matthaeus, T. N. Parashar, R. Chhiber, D. Ruffolo, M. L. Goldstein, B. A. Maruca, A. Chasapis, R. Qudsi, D. J. McComas, E. R. Christian, J. R. Szalay, C. J. Joyce, J. Giacalone, N. A. Schwadron, D. G. Mitchell, M. E. Hill, M. E. Wiedenbeck, R. L. McNutt, M. I. Desai, Stuart D. Bale, J. W. Bonnell, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, M. Velli, J. C. Kasper, K. E. Korreck, M. Stevens, A. W. Case, and N. Raouafi
Published: 2020
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16. Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe

Author: Riddhi Bandyopadhyay, M. L. Goldstein, B. A. Maruca, W. H. Matthaeus, T. N. Parashar, D. Ruffolo, R. Chhiber, A. Usmanov, A. Chasapis, R. Qudsi, Stuart D. Bale, J. W. Bonnell, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Robert J. MacDowall, David M. Malaspina, Marc Pulupa, J. C. Kasper, K. E. Korreck, A. W. Case, M. Stevens, P. Whittlesey, D. Larson, R. Livi, K. G. Klein, M. Velli, and N. Raouafi
Published: 2020
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17. Theory of Cosmic Ray Transport in the Heliosphere

Author: N. Eugene Engelbrecht, F. Effenberger, V. Florinski, M. S. Potgieter, D. Ruffolo, R. Chhiber, A. V. Usmanov, J. S. Rankin, and P. L. Els
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Abstract: Modelling the transport of cosmic rays (CRs) in the heliosphere represents a global challenge in the field of heliophysics, in that such a study, if it were to be performed from first principles, requires the careful modelling of both large scale heliospheric plasma quantities (such as the global structure of the heliosphere, or the heliospheric magnetic field) and small scale plasma quantities (such as various turbulence-related quantities). Here, recent advances in our understanding of the transport of galactic cosmic rays are reviewed, with an emphasis on new developments pertaining to their transport coefficients, with a special emphasis on novel theoretical and numerical simulation results, as well as the CR transport studies that employ them. Furthermore, brief reviews are given of recent progress in CR focused transport modelling, as well as the modelling of non-diffusive CR transport.
Published: 2022
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18. Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Author: Zhen, Cao, F, Aharonian, Q, An, Axikegu, L X, Bai, Y X, Bai, Y W, Bao, D, Bastieri, X J, Bi, Y J, Bi, H, Cai, J T, Cai, Zhe, Cao, J, 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, S H, Chen, S Z, Chen, T L, Chen, X L, Chen, Y, Chen, N, Cheng, Y D, Cheng, S W, Cui, X H, Cui, Y D, Cui, B D'Ettorre, Piazzoli, B Z, Dai, H L, Dai, Z G, Dai, Danzengluobu, D, Della Volpe, X J, Dong, K K, Duan, J H, Fan, Y Z, Fan, Z X, Fan, J, Fang, K, Fang, C F, Feng, L, Feng, S H, Feng, Y L, Feng, B, Gao, C D, Gao, L Q, Gao, Q, Gao, W, Gao, M M, Ge, L S, Geng, G H, Gong, Q B, Gou, M H, Gu, F L, Guo, J G, Guo, X L, Guo, Y Q, Guo, Y Y, Guo, Y A, Han, H H, He, H N, He, J C, He, S L, He, X B, He, Y, He, M, Heller, Y K, Hor, C, Hou, X, Hou, H B, Hu, S, Hu, S C, Hu, X J, Hu, D H, Huang, Q L, Huang, W H, Huang, X T, Huang, X Y, Huang, Z C, Huang, F, Ji, X L, Ji, H Y, Jia, K, Jiang, Z J, Jiang, C, Jin, T, Ke, D, Kuleshov, K, Levochkin, B B, Li, Cheng, Li, Cong, Li, F, Li, H B, Li, H C, Li, H Y, Li, Jian, Li, Jie, Li, K, Li, W L, Li, X R, Li, Xin, Li, Y, Li, Y Z, Li, Zhe, Li, Zhuo, Li, E W, Liang, Y F, Liang, S J, Lin, B, Liu, C, Liu, D, Liu, H, Liu, H D, Liu, J, Liu, J L, Liu, J S, Liu, J Y, Liu, M Y, Liu, R Y, Liu, S M, Liu, W, Liu, Y, Liu, Y N, Liu, Z X, Liu, W J, Long, R, Lu, H K, Lv, B Q, Ma, L L, Ma, X H, Ma, J R, Mao, A, Masood, Z, Min, W, Mitthumsiri, T, Montaruli, Y C, Nan, B Y, Pang, P, Pattarakijwanich, Z Y, Pei, M Y, Qi, Y Q, Qi, B Q, Qiao, J J, Qin, D, Ruffolo, V, Rulev, A, Sáiz, L, Shao, O, Shchegolev, X D, Sheng, J R, Shi, H C, Song, Yu V, Stenkin, V, Stepanov, Y, Su, Q N, Sun, X N, Sun, Z B, Sun, P H T, Tam, Z B, Tang, W W, Tian, B D, Wang, C, Wang, H, Wang, H G, Wang, J C, Wang, J S, Wang, L P, Wang, L Y, Wang, R N, Wang, W, Wang, X G, Wang, X J, Wang, X Y, Wang, Y, Wang, Y D, Wang, Y J, Wang, Y P, 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, S, Wu, W X, Wu, X F, Wu, S Q, Xi, J, Xia, J J, Xia, G M, Xiang, D X, Xiao, G, Xiao, H B, Xiao, G G, Xin, Y L, Xin, Y, Xing, D L, Xu, R X, Xu, L, Xue, D H, Yan, J Z, Yan, C W, Yang, F F, Yang, J Y, Yang, L L, Yang, M J, Yang, R Z, Yang, S B, Yang, Y H, Yao, Z G, Yao, Y M, Ye, L Q, Yin, N, Yin, X H, You, Z Y, You, Y H, Yu, Q, Yuan, H D, Zeng, T X, Zeng, W, Zeng, Z K, Zeng, M, Zha, X X, Zhai, B B, Zhang, H M, Zhang, H Y, Zhang, J L, Zhang, J W, Zhang, L X, Zhang, Li, Zhang, Lu, Zhang, P F, Zhang, P P, Zhang, R, Zhang, S R, Zhang, S S, Zhang, X, Zhang, X P, Zhang, Y F, Zhang, Y L, Zhang, Yi, Zhang, Yong, Zhang, B, Zhao, J, Zhao, L, Zhao, L Z, Zhao, S P, Zhao, F, Zheng, Y, Zheng, B, Zhou, H, Zhou, J N, Zhou, P, Zhou, R, Zhou, X X, Zhou, C G, Zhu, F R, Zhu, H, Zhu, K J, Zhu, and X, Zuo
Subjects: General Physics and Astronomy
Abstract: Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.
Published: 2021

19. Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

Author: F, Aharonian, Q, An, Axikegu, L X, Bai, Y X, Bai, Y W, Bao, D, Bastieri, X J, Bi, Y J, Bi, H, Cai, J T, Cai, Z, Cao, J, Chang, J F, Chang, X C, Chang, B M, Chen, J, Chen, L, Chen, M J, Chen, M L, Chen, Q H, Chen, S H, Chen, S Z, Chen, T L, Chen, X L, Chen, Y, Chen, N, Cheng, Y D, Cheng, S W, Cui, X H, Cui, Y D, Cui, B Z, Dai, H L, Dai, Z G, Dai, Danzengluobu, D, Della Volpe, B, D'Ettorre Piazzoli, X J, Dong, J H, Fan, Y Z, Fan, Z X, Fan, J, Fang, K, Fang, C F, Feng, L, Feng, S H, Feng, Y L, Feng, B, Gao, C D, Gao, Q, Gao, W, Gao, M M, Ge, L S, Geng, G H, Gong, Q B, Gou, M H, Gu, J G, Guo, X L, Guo, Y Q, Guo, Y Y, Guo, Y A, Han, H H, He, H N, He, J C, He, S L, He, X B, He, Y, He, M, Heller, Y K, Hor, C, Hou, X, Hou, H B, Hu, S, Hu, S C, Hu, X J, Hu, D H, Huang, Q L, Huang, W H, Huang, X T, Huang, Z C, Huang, F, Ji, X L, Ji, H Y, Jia, K, Jiang, Z J, Jiang, C, Jin, D, Kuleshov, K, Levochkin, B B, Li, C, Li, F, Li, H B, Li, H C, Li, H Y, Li, J, Li, K, Li, W L, Li, X, Li, X R, Li, Y, Li, Y Z, Li, Z, Li, E W, Liang, Y F, Liang, S J, Lin, B, Liu, C, Liu, D, Liu, H, Liu, H D, Liu, J, Liu, J L, Liu, J S, Liu, J Y, Liu, M Y, Liu, R Y, Liu, S M, Liu, W, Liu, Y N, Liu, Z X, Liu, W J, Long, R, Lu, H K, Lv, B Q, Ma, L L, Ma, X H, Ma, J R, Mao, A, Masood, W, Mitthumsiri, T, Montaruli, Y C, Nan, B Y, Pang, P, Pattarakijwanich, Z Y, Pei, M Y, Qi, D, Ruffolo, V, Rulev, A, Sáiz, L, Shao, O, Shchegolev, X D, Sheng, J R, Shi, H C, Song, Yu V, Stenkin, V, Stepanov, Q N, Sun, X N, Sun, Z B, Sun, P H T, Tam, Z B, Tang, W W, Tian, B D, Wang, C, Wang, H, Wang, H G, Wang, J C, Wang, J S, Wang, L P, Wang, L Y, Wang, R N, Wang, W, Wang, X G, Wang, X J, Wang, X Y, Wang, Y D, Wang, Y J, Wang, Y P, Wang, Z, Wang, Z H, Wang, Z X, Wang, D M, Wei, J J, Wei, Y J, Wei, T, Wen, C Y, Wu, H R, Wu, S, Wu, W X, Wu, X F, Wu, S Q, Xi, J, Xia, J J, Xia, G M, Xiang, G, Xiao, H B, Xiao, G G, Xin, Y L, Xin, Y, Xing, D L, Xu, R X, Xu, L, Xue, D H, Yan, C W, Yang, F F, Yang, J Y, Yang, L L, Yang, M J, Yang, R Z, Yang, S B, Yang, Y H, Yao, Z G, Yao, Y M, Ye, L Q, Yin, N, Yin, X H, You, Z Y, You, Y H, Yu, Q, Yuan, H D, Zeng, T X, Zeng, W, Zeng, Z K, Zeng, M, Zha, X X, Zhai, B B, Zhang, H M, Zhang, H Y, Zhang, J L, Zhang, J W, Zhang, L, Zhang, L X, Zhang, P F, Zhang, P P, Zhang, R, Zhang, S R, Zhang, S S, Zhang, X, Zhang, X P, Zhang, Y, Zhang, Y F, Zhang, Y L, Zhang, B, Zhao, J, Zhao, L, Zhao, L Z, Zhao, S P, Zhao, F, Zheng, Y, Zheng, B, Zhou, H, Zhou, J N, Zhou, P, Zhou, R, Zhou, X X, Zhou, C G, Zhu, F R, Zhu, H, Zhu, K J, Zhu, X, Zuo, and X Y, Huang
Abstract: We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E25 TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160 TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.
Published: 2021

20. Discovery of the Ultra-high energy gamma-ray source LHAASO J2108+5157

Author: Zhen Cao, F. Aharonian, Q. An, null Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Zhe Cao, J. 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, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. D’Ettorre Piazzoli, B. Z. Dai, H. L. Dai, Z. G. Dai, Dan-Zeng Dan-Zeng-Luo-Bu, D. della Volpe, X. J. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, L. Q. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, X. Y. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, T. Ke, D. Kuleshov, K. Levochkin, B. B. Li, Cheng Li, Cong Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. R. Li, Xin Li, Y. Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, Z. Min, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, Y. Q. Qi, B. Q. Qiao, J. J. Qin, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. Y. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. 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, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, J. Z. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. X. Zhang, Li Zhang, Lu Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Y. L. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, and X. Zuo
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Molecular cloud, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Gamma ray, Flux, Sigma, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Gamma-ray astronomy, Space and Planetary Science, Energy spectrum, Ultrahigh energy, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the discovery of a UHE gamma-ray source, LHAASO J2108+5157, by analyzing the LHAASO-KM2A data of 308.33 live days. Significant excess of gamma-ray induced showers is observed in both energy bands of 25-100 TeV and $\gt$100 TeV with 9.5 sigma and 8.5 sigma, respectively. This source is not significantly favored as an extensive source with the angular extension smaller than the point-spread function of KM2A. The measured energy spectrum from 20 to 200 TeV can be approximately described by a power-law function with an index of -2.83$\pm$ 0.18stat. 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, deeper multiwavelength observations will help to shed new light on this intriguing UHE source., Comment: 12 pages, 7 figures, accepted by ApJL
Published: 2021
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21. Magnetic Reconnection inside a Flux Transfer Event-like structure in Magnetopause Kelvin-Helmholtz Waves

Author: Rungployphan Kieokaew, Benoit Lavraud, C Foullon, S Toledo-Redondo, N Fargette, K.-J Hwang, K Malakit, D Ruffolo, M Øieroset, T D Phan, H Hasegawa, S Fadanelli, L Avanov, J Burch, D J Gershman, B Giles, J Dorelli, V Génot, C Jacquey, T Moore, W Paterson, C Pollock, A Rager, Y Saito, J.-A Sauvaud, C Schiff, Y Vernisse, and E Penou
Published: 2020
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22. Corrigendum to 'Performance test of the electromagnetic particle detectors for the LHAASO experiment' [Nucl. Instrum. Methods Phys. Res. A 1001 (2021) 165193]

Author: F. Aharonian, Q. An, null Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, null Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. Li, B.B. Li, C. Li, F. Li, H. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, M.Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, H.C. Song, Yu.V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H. T. Tam, Z.B. Tang, W.W. Tian, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, X. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, and X. Zuo
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Detector, Particle, Instrumentation
Published: 2022
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23. Performance of LHAASO-WCDA and observation of the Crab Nebula as a standard candle *

Author: F. Aharonian, Q. An, 克古 Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, 罗布 Danzengluobu, D. della Volpe, B. D'Ettorre Piazzoli, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B.B. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, M.Y. Qi, B.Q. Qiao, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, H.C. Song, Yu.V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H.T. Tam, Z.B. Tang, W.W. Tian, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, X. Zuo, and (The LHAASO Collaboration)
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Cherenkov detector, Point source, Astrophysics::High Energy Astrophysical Phenomena, Cosmic distance ladder, Gamma ray, Astronomy and Astrophysics, Cosmic ray, Astrophysics, 01 natural sciences, law.invention, Crab Nebula, law, 0103 physical sciences, Spectral energy distribution, Angular resolution, 010306 general physics, Instrumentation
Abstract: The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April 2019. The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves a sensitivity of 65 mCU per year, with a statistical threshold of 5 . To accomplish this, a 97.7% cosmic-ray background rejection rate around 1 TeV and 99.8% around 6 TeV with an approximate photon acceptance of 50% is achieved after applying an algorithm to separate gamma-induced showers. The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45° at 1 TeV and better than 0.2° above 6 TeV, with a pointing accuracy better than 0.05°. These values all match the design specifications. The energy resolution is found to be 33% for gamma rays around 6 TeV. The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.
Published: 2021
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24. Geometrical reconstruction of fluorescence events observed by the LHAASO experiment *

Author: F. Aharonian, Q. An, null Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, null Danzengluobu, D. della Volpe, B. D'Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu.V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, and X. Zuo
Subjects: Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Detector, Resolution (electron density), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Cosmic ray, 01 natural sciences, Fluorescence, law.invention, Telescope, Optics, law, 0103 physical sciences, Trajectory, Range (statistics), 010306 general physics, business, Instrumentation, Cherenkov radiation
Abstract: The LHAASO-WFCTA experiment, which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique, uses a new generation of high-performance telescopes. To ensure that the experiment has excellent detection capability associated with the measurement of the energy spectrum, the primary composition of cosmic rays, and so on, an accurate geometrical reconstruction of air-shower events is fundamental. This paper describes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA (Wide Field of view Cherenkov/Fluorescence Telescope Array) detectors. Two approaches, which take full advantage of the WFCTA detectors, are investigated. One is the stereo-angular method, which uses the pointing of triggered SiPMs in the shower trajectory, and the other is the stereo-timing method, which uses the triggering time of the fired SiPMs. The results show that both methods have good geometrical resolution; the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.
Published: 2021
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25. Observation of the Crab Nebula with LHAASO-KM2A − a performance study *

Author: F. Aharonian, Q. An, 克古 Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, 罗布 Danzengluobu, D. della Volpe, B. D'Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, and X. Zuo
Subjects: Physics, Nuclear and High Energy Physics, High energy, 010308 nuclear & particles physics, Cosmic distance ladder, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Crab Nebula, 0103 physical sciences, Energy spectrum, 010306 general physics, Instrumentation, Energy (signal processing)
Abstract: A sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV. Even though the detector construction is still underway, half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the KM2A data analysis pipeline and the first observation of the Crab Nebula, a standard candle in very high energy γ-ray astronomy. We detect γ-ray signals from the Crab Nebula in both energy ranges of 10 100 TeV and 100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance, including angular resolution, pointing accuracy and cosmic-ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE = (1.13 0.05 0.08 ) 10 (E/20 TeV) cm s TeV . It is consistent with previous measurements by other experiments. This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena, such as cosmic PeVatrons, might be discovered.
Published: 2021
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26. Preliminary analysis of the Changvan neutron monitor operation in latitude surveys during 2019-2020

Author: S Khamphakdee, P Jiang, P Chuanraksasat, W Nuntiyakul, D Ruffolo, A Sáiz, P Evenson, K Munakata, J Madsen, B Soonthorntham, S Komonjinda, and R Macatangay
Subjects: History, Neutron monitor, Environmental science, Neutron, Computer Science Applications, Education, Preliminary analysis, Remote sensing, Latitude
Abstract: Within our solar system, space weather is influenced by the solar wind and the interplanetary magnetic field carried by the solar wind plasma. Severe solar storms can expose people to increased radiation levels, shut down electrical systems, and interfere with radio signals. Space weather probably affects the weather and climate on our planet, but we do not yet have a precise understanding of the influence. Some aspects of space weather can be monitored at ground level with a detector, such as a “neutron monitor,” that measures cosmic rays from outer space. We have developed a portable “Changvan” neutron monitor to investigate the energy spectrum of cosmic rays and its solar modulation, i.e., variations over the typically 11-year sunspot cycle. The Changvan monitor located inside the insulated shipping container comprises three proportional counters in the standard-design neutron monitors, but the central counter is deficient in the lead producer. This monitor records counting rates during passage through a range of geomagnetic latitudes, which this technique is called “latitude survey.” The ultimate goal of the latitude surveys is to help accurately interpret data from every neutron monitor in a space environment that is always changing. In this work, we show a preliminary analysis of Changvan monitor data collected from two latitude surveys during 2019-2020 on the Chinese icebreaker MV Xue Long from Shanghai, China to Zhongshan station, Antarctica and back. A strong anti-correlation can be observed between the Changvan monitor count rate and barometric pressure.
Published: 2021
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27. Preliminary analysis of ice Cherenkov detector operation during a latitude survey

Author: Y Tangjai, A Pagwhan, W Nuntiyakul, D Ruffolo, J W Bieber, J Clem, P S Mangeard, R Pyle, and A Sáiz
Subjects: History, Spectrometer, Meteorology, Cherenkov detector, Cosmic ray, Computer Science Applications, Education, IceCube Neutrino Observatory, Latitude, law.invention, Preliminary analysis, Earth's magnetic field, law, Environmental science, Cherenkov radiation
Abstract: IceTop, the surface component of IceCube Neutrino Observatory at the South Pole, studies cosmic ray air showers with an array of ice Cherenkov detectors typically referred to as “IceTop Tanks.” In November 2009, collaborators from the University of Delaware, UW River Falls, and Uppsala University loaded an insulated shipping container containing an IceTop Tank on the icebreaker Oden which traversed the Atlantic Ocean from Helsingborg, Sweden to McMurdo, Antarctica, and return. Over an approximately 6-month interval, Oden carried the IceTop Tank through a wide range of geomagnetic cut-offs. The data obtained will allow the energy dependent effective area (yield function) to be determined using the Earth as a magnet spectrometer. The ultimate goal of the project is to calibrate the IceTop Tanks to study cosmic rays in the GeV primary energy range. We will report preliminary results for determining the yield functions.
Published: 2021
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28. Balancing network and business planning for cable telephony

Author: D. Doherty, D. Ruffolo, M. Glapa, F. Magee, S. Kamat, and S. Prakash
Subjects: Network planning and design, Voice over IP, Artifact-centric business process model, business.industry, Computer science, New business development, Triple play (telecommunications), Telephony, Business case, business, Cable telephony, Telecommunications
Abstract: The past several years upgrading the cable networks to support next generation end-user services, multiple system operators (MSOs) are looking for new ways to generate incremental revenue while reducing subscriber churn. It is widely believed that the so-called "triple play " of voice, video, and data services will help the MSOs to achieve these goals. However, offering voice end-user services is a complex issue, both from a business and a technical perspective. The MSO must decide what markets to enter, how to price the offerings, what technology and vendors to select, how to design the network, and how to ensure optimal performance and reliability. An integrated approach to business and technology planning allows key economic trade-offs in design and launching new voice services that can't be done piecemeal. A modeling approach that incorporates both technical and business aspects of deploying IP based cable telephony is critical to success. A computer-based model was developed that allows the user to determine how changes in any market, business, or engineering parameters can impact the overall business case (NPV, discounted payback period, internal rate of return, etc.) and the network design (equipment sizing, performance, reliability, etc.). This work will describe the components of business and network planning for cable telephony, the modeling approach, and sample results for some hypothetical scenarios.
Published: 2004
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29. NANP: one voice for NPs

Author: D, Ruffolo
Subjects: Societies, Nursing, Humans, Nurse Practitioners, United States
Published: 1998

30. Tracking Cosmic-Ray Spectral Variation during 2007–2018 Using Neutron Monitor Time-delay Measurements.

Author: C. Banglieng, H. Janthaloet, D. Ruffolo, A. Sáiz, W. Mitthumsiri, P. Muangha, P. Evenson, T. Nutaro, R. Pyle, S. Seunarine, J. Madsen, P.-S. Mangeard, and R. Macatangay
Subjects: COSMIC rays, PRECIPITABLE water, GEOMAGNETISM, SOLAR cycle, NEUTRONS, SOLAR activity, NEUTRON multiplicity
Abstract: The energy spectrum of Galactic cosmic-ray (GCR) ions at Earth varies with solar activity as these ions cross the heliosphere. Thus, this “solar modulation” of GCRs provides remote sensing of heliospheric conditions throughout the ∼11 yr sunspot cycle and ∼22 yr solar magnetic cycle. A neutron monitor (NM) is a stable ground-based detector that measures cosmic-ray rate variations above a geomagnetic or atmospheric cutoff rigidity with high precision (∼0.1%) over such timescales. Furthermore, we developed electronics and analysis techniques to indicate variations in the cosmic-ray spectral index using neutron time-delay data from a single station. Here we study solar modulation using neutron time-delay histograms from two high-altitude NM stations: (1) the Princess Sirindhorn Neutron Monitor at Doi Inthanon, Thailand, with the world’s highest vertical geomagnetic cutoff rigidity, 16.7 GV, from 2007 December to 2018 April; and (2) the South Pole NM, with an atmosphere-limited cutoff of ∼1 GV, from 2013 December to 2018 April. From these histograms, we extract the leader fraction L, i.e., inverse neutron multiplicity, as a proxy of a GCR spectral index above the cutoff. After correction for pressure and precipitable water vapor variations, we find that L roughly correlates with the count rate but also exhibits hysteresis, implying a change in spectral shape after a solar magnetic polarity reversal. Spectral variations due to Forbush decreases, 27 day variations, and a ground-level enhancement are also indicated. These methods enhance the high-precision GCR spectral information from the worldwide NM network and extend it to higher rigidity. [ABSTRACT FROM AUTHOR]
Published: 2020
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31. Clustering of Intermittent Magnetic and Flow Structures near Parker Solar Probe’s First Perihelion—A Partial-variance-of-increments Analysis.

Author: Rohit Chhiber, M L. Goldstein, B. A. Maruca, A. Chasapis, W. H. Matthaeus, D. Ruffolo, R. Bandyopadhyay, T. N. Parashar, R. Qudsi, T. Dudok de Wit, S. D. Bale, J. W. Bonnell, K. Goetz, P. R. Harvey, R. J. MacDowall, D. Malaspina, M. Pulupa, J. C. Kasper, K. E. Korreck, and A. W. Case
Published: 2020
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32. X-Rays from e ± Pair Halos.

Author: A. Eungwanichayapant, W. Luangtip, W. Maithong, and D. Ruffolo
Subjects: X-rays, PHOTON pairs, MAGNETIC fields, GAMMA ray spectrometry
Abstract: It was previously suggested that e± pair halos could be observed in γ-rays. Searching for pair halos is a challenging topic in γ-ray astronomy that has not yet yielded a convincing detection for an individual object. Here we propose that X-ray observations could reveal the existence of e± pair halos. To support our suggestion, we computed the observed energy and spatial distribution of X-ray photons from the pair halos and check the feasibility of pair halo detection by current and future X-ray observatories. The results show that current X-ray missions could register a positive signal for the pair halos created under some conditions. For a magnetic field (B) of ∼1 μG, the X-ray could be observable for a seed gamma-ray energy of TeV. If TeV, the observable range of B would be B ≳ 300 nG. [ABSTRACT FROM AUTHOR]
Published: 2019
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33. Galactic Cosmic-Ray Anistropy During the Forbush Decrease Starting 2013 April 13.

Author: U. Tortermpun, D. Ruffolo, and J. W. Bieber
Published: 2018
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34. Coronal Heating Topology: The Interplay of Current Sheets and Magnetic Field Lines.

Author: A. F. Rappazzo, W. H. Matthaeus, D. Ruffolo, M. Velli, and S. Servidio
Subjects: SOLAR magnetic fields, SOLAR corona, MAGNETOHYDRODYNAMICS, PLASMA turbulence, SOLAR flares
Abstract: The magnetic topology and field line random walk (FLRW) properties of a nanoflare-heated and magnetically confined corona are investigated in the reduced magnetohydrodynamic regime. Field lines originating from current sheets form coherent structures, called current sheet connected (CSC) regions, which extend around them. CSC FLRW is strongly anisotropic, with preferential diffusion along the current sheets’ in-plane length. CSC FLRW properties remain similar to those of the entire ensemble but exhibit enhanced mean square displacements and separations due to the stronger magnetic field intensities in CSC regions. The implications for particle acceleration and heat transport in the solar corona and wind, and for solar moss formation are discussed. [ABSTRACT FROM AUTHOR]
Published: 2017
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35. Cosmic-Ray Diffusion Coefficients throughout the Inner Heliosphere from a Global Solar Wind Simulation.

Author: R. Chhiber, P. Subedi, A. V. Usmanov, W. H. Matthaeus, D. Ruffolo, M. L. Goldstein, and T. N. Parashar
Published: 2017
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36. Charged Particle Diffusion in Isotropic Random Magnetic Fields.

Author: P. Subedi, W. Sonsrettee, P. Blasi, D. Ruffolo, W. H. Matthaeus, D. Montgomery, P. Chuychai, P. Dmitruk, M. Wan, T. N. Parashar, and R. Chhiber
Subjects: COSMIC rays, CHARGED particle accelerators, ASTROPHYSICAL magnetic fields, DIFFUSION coefficients, TURBULENCE
Abstract: The investigation of the diffusive transport of charged particles in a turbulent magnetic field remains a subject of considerable interest. Research has most frequently concentrated on determining the diffusion coefficient in the presence of a mean magnetic field. Here we consider the diffusion of charged particles in fully three-dimensional isotropic turbulent magnetic fields with no mean field, which may be pertinent to many astrophysical situations. We identify different ranges of particle energy depending upon the ratio of Larmor radius to the characteristic outer length scale of turbulence. Two different theoretical models are proposed to calculate the diffusion coefficient, each applicable to a distinct range of particle energies. The theoretical results are compared to those from computer simulations, showing good agreement. [ABSTRACT FROM AUTHOR]
Published: 2017
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37. SIMULATIONS OF LATERAL TRANSPORT AND DROPOUT STRUCTURE OF ENERGETIC PARTICLES FROM IMPULSIVE SOLAR FLARES.

Author: P. Tooprakai, A. Seripienlert, D. Ruffolo, P. Chuychai, and W. H. Matthaeus
Subjects: TURBULENCE, SOLAR flares, FOURIER transform infrared spectroscopy, MAGNETIC fields, PARTICLE density (Nuclear chemistry)
Abstract: We simulate trajectories of energetic particles from impulsive solar flares for 2D+slab models of magnetic turbulence in spherical geometry to study dropout features, i.e., sharp, repeated changes in the particle density. Among random-phase realizations of two-dimensional (2D) turbulence, a spherical harmonic expansion can generate homogeneous turbulence over a sphere, but a 2D fast Fourier transform (FFT) locally mapped onto the lateral coordinates in the region of interest is much faster computationally, and we show that the results are qualitatively similar. We then use the 2D FFT field as input to a 2D MHD simulation, which dynamically generates realistic features of turbulence such as coherent structures. The magnetic field lines and particles spread non-diffusively (ballistically) to a patchy distribution reaching up to 25° from the injection longitude and latitude at r ∼ 1 au. This dropout pattern in field line trajectories has sharper features in the case of the more realistic 2D MHD model, in better qualitative agreement with observations. The initial dropout pattern in particle trajectories is relatively insensitive to particle energy, though the energy affects the pattern’s evolution with time. We make predictions for future observations of solar particles near the Sun (e.g., at 0.25 au), for which we expect a sharp pulse of outgoing particles along the dropout pattern, followed by backscattering that first remains close to the dropout pattern and later exhibits cross-field transport to a distribution that is more diffusive, yet mostly contained within the dropout pattern found at greater distances. [ABSTRACT FROM AUTHOR]
Published: 2016
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38. EVOLUTION OF THE MAGNETIC FIELD LINE DIFFUSION COEFFICIENT AND NON-GAUSSIAN STATISTICS.

Author: A. P. Snodin, D. Ruffolo, and W. H. Matthaeus
Subjects: *MAGNETIC reconnection, *MATHEMATICAL models of turbulence, *DIFFUSION coefficients, *ORDINARY differential equations, *GAUSSIAN mixture models
Abstract: The magnetic field line random walk (FLRW) plays an important role in the transport of energy and particles in turbulent plasmas. For magnetic fluctuations that are transverse or almost transverse to a large-scale mean magnetic field, theories describing the FLRW usually predict asymptotic diffusion of magnetic field lines perpendicular to the mean field. Such theories often depend on the assumption that one can relate the Lagrangian and Eulerian statistics of the magnetic field via Corrsin’s hypothesis, and additionally take the distribution of magnetic field line displacements to be Gaussian. Here we take an ordinary differential equation (ODE) model with these underlying assumptions and test how well it describes the evolution of the magnetic field line diffusion coefficient in 2D+slab magnetic turbulence, by comparisons to computer simulations that do not involve such assumptions. In addition, we directly test the accuracy of the Corrsin approximation to the Lagrangian correlation. Over much of the studied parameter space we find that the ODE model is in fairly good agreement with computer simulations, in terms of both the evolution and asymptotic values of the diffusion coefficient. When there is poor agreement, we show that this can be largely attributed to the failure of Corrsin’s hypothesis rather than the assumption of Gaussian statistics of field line displacements. The degree of non-Gaussianity, which we measure in terms of the kurtosis, appears to be an indicator of how well Corrsin’s approximation works. [ABSTRACT FROM AUTHOR]
Published: 2016
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39. MAGNETIC FIELD LINE RANDOM WALK IN ISOTROPIC TURBULENCE WITH VARYING MEAN FIELD.

Author: W. Sonsrettee, P. Subedi, D. Ruffolo, W. H. Matthaeus, A. P. Snodin, P. Wongpan, P. Chuychai, G. Rowlands, and S. Vyas
Published: 2016
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40. NON-AXISYMMETRIC PERPENDICULAR DIFFUSION OF CHARGED PARTICLES AND THEIR TRANSPORT ACROSS TANGENTIAL MAGNETIC DISCONTINUITIES.

Author: R. D. Strauss, J. A. le Roux, N. E. Engelbrecht, D. Ruffolo, and P. Dunzlaff
Subjects: CHARGED particle accelerators, TANGENTIAL force, SOLAR wind, MAGNETIC fields, MAGNETIC structure
Abstract: We investigate the transport of charged particles across magnetic discontinuities, focusing specifically on stream interfaces associated with co-rotating interaction regions in the solar wind. We argue that the magnetic field fluctuations perpendicular to the magnetic discontinuity, and usually also perpendicular to the mean magnetic field, are strongly damped in the vicinity of such a magnetic structure, leading to anisotropic perpendicular diffusion. Assuming that perpendicular diffusion arises from drifts in a turbulent magnetic field, we adopt a simplified approach to derive the relevant perpendicular diffusion coefficient. This approach, which we believe gives the correct principal dependences as expected from more elaborate calculations, allows us to investigate transport in different turbulent geometries, such as longitudinal compressional turbulence that may be present near the heliopause. Although highly dependent on the (possibly anisotropic) perpendicular length scales and turbulence levels, we generally find perpendicular diffusion to be strongly damped at magnetic discontinuities, which may in turn provide an explanation for the large particle gradients associated with these structures. [ABSTRACT FROM AUTHOR]
Published: 2016
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41. MONITORING SHORT-TERM COSMIC-RAY SPECTRAL VARIATIONS USING NEUTRON MONITOR TIME-DELAY MEASUREMENTS.

Author: D. Ruffolo, A. Sáiz, P.-S. Mangeard, N. Kamyan, P. Muangha, T. Nutaro, S. Sumran, C. Chaiwattana, N. Gasiprong, C. Channok, C. Wuttiya, M. Rujiwarodom, P. Tooprakai, B. Asavapibhop, J. W. Bieber, J. Clem, P. Evenson, and K. Munakata
Subjects: *COSMIC ray showers, *GALACTIC cosmic rays, *TIME delay systems, *CORONAL mass ejections, *METAPHYSICAL cosmology
Abstract: Neutron monitors (NMs) are ground-based detectors of cosmic-ray showers that are widely used for high-precision monitoring of changes in the Galactic cosmic-ray (GCR) flux due to solar storms and solar wind variations. In the present work, we show that a single neutron monitor station can also monitor short-term changes in the GCR spectrum, avoiding the systematic uncertainties in comparing data from different stations, by means of NM time-delay histograms. Using data for 2007–2014 from the Princess Sirindhorn Neutron Monitor, a station at Doi Inthanon, Thailand, with the world’s highest vertical geomagnetic cutoff rigidity of 16.8 GV, we have developed an analysis of time-delay histograms that removes the chance coincidences that can dominate conventional measures of multiplicity. We infer the “leader fraction” L of neutron counts that do not follow a previous neutron count in the same counter from the same atmospheric secondary, which is inversely related to the actual multiplicity and increases for increasing GCR spectral index. After correction for atmospheric pressure and water vapor, we find that L indicates substantial short-term GCR spectral hardening during some but not all Forbush decreases in GCR flux due to solar storms. Such spectral data from Doi Inthanon provide information about cosmic-ray energies beyond the Earth’s maximum geomagnetic cutoff, extending the reach of the worldwide NM network and opening a new avenue in the study of short-term GCR decreases. [ABSTRACT FROM AUTHOR]
Published: 2016
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42. DYNAMICAL FIELD LINE CONNECTIVITY IN MAGNETIC TURBULENCE.

Author: D. Ruffolo and W. H. Matthaeus
Subjects: *ASTROPHYSICS research, *MAGNETIC fields, *CORONAL holes, *SOLAR corona, *ASTRONOMY
Abstract: Point-to-point magnetic connectivity has a stochastic character whenever magnetic fluctuations cause a field line random walk, but this can also change due to dynamical activity. Comparing the instantaneous magnetic connectivity from the same point at two different times, we provide a nonperturbative analytic theory for the ensemble average perpendicular displacement of the magnetic field line, given the power spectrum of magnetic fluctuations. For simplicity, the theory is developed in the context of transverse turbulence, and is numerically evaluated for the noisy reduced MHD model. Our formalism accounts for the dynamical decorrelation of magnetic fluctuations due to wave propagation, local nonlinear distortion, random sweeping, and convection by a bulk wind flow relative to the observer. The diffusion coefficient DX of the time-differenced displacement becomes twice the usual field line diffusion coefficient Dx at large time displacement t or large distance z along the mean field (corresponding to a pair of uncorrelated random walks), though for a low Kubo number (in the quasilinear regime) it can oscillate at intermediate values of t and z. At high Kubo number the dynamical decorrelation decays mainly from the nonlinear term and DX tends monotonically toward 2Dx with increasing t and z. The formalism and results presented here are relevant to a variety of astrophysical processes, such as electron transport and heating patterns in coronal loops and the solar transition region, changing magnetic connection to particle sources near the Sun or at a planetary bow shock, and thickening of coronal hole boundaries. [ABSTRACT FROM AUTHOR]
Published: 2015
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43. Stringent Tests of Lorentz Invariance Violation from LHAASO Observations of GRB 221009A.

Author: Cao Z, Aharonian F, Axikegu, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Bian W, Bukevich AV, Cao Q, Cao WY, Cao Z, Chang J, Chang JF, Chen AM, Chen ES, Chen HX, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen S, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng N, Cheng YD, Cui MY, Cui SW, Cui XH, Cui YD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Dong XQ, Duan KK, Fan JH, Fan YZ, Fang J, Fang JH, Fang K, Feng CF, Feng H, Feng L, Feng SH, Feng XT, Feng Y, Feng YL, Gabici S, Gao B, Gao CD, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Giacinti G, Gong GH, Gou QB, Gu MH, Guo FL, Guo XL, Guo YQ, Guo YY, Han YA, Hasan M, He HH, He HN, He JY, He Y, Hor YK, Hou BW, Hou C, Hou X, Hu HB, Hu Q, Hu SC, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Ji XL, Jia HY, Jia K, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Karpikov I, Kuleshov D, Kurinov K, Li BB, Li CM, Li C, Li C, Li D, Li F, Li HB, Li HC, Li J, Li J, Li K, Li SD, Li WL, Li WL, Li XR, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu DB, Liu H, Liu HD, Liu J, Liu JL, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Luo Q, Luo Y, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Min Z, Mitthumsiri W, Mu HJ, Nan YC, Neronov A, Ou LJ, Pattarakijwanich P, Pei ZY, Qi JC, Qi MY, Qiao BQ, Qin JJ, Raza A, Ruffolo D, Sáiz A, Saeed M, Semikoz D, Shao L, Shchegolev O, Sheng XD, Shu FW, Song HC, Stenkin YV, Stepanov V, Su Y, Sun DX, Sun QN, Sun XN, Sun ZB, Takata J, Tam PHT, Tang QW, Tang R, Tang ZB, Tian WW, Wang C, Wang CB, Wang GW, Wang HG, Wang HH, Wang JC, Wang K, Wang K, Wang LP, Wang LY, Wang PH, Wang R, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu QW, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xiang GM, Xiao DX, Xiao G, Xin YL, Xing Y, Xiong DR, Xiong Z, Xu DL, Xu RF, Xu RX, Xu WL, Xue L, Yan DH, Yan JZ, Yan T, Yang CW, Yang CY, Yang F, Yang FF, Yang LL, Yang MJ, Yang RZ, Yang WX, Yao YH, Yao ZG, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zha M, Zhang BB, Zhang F, Zhang H, Zhang HM, Zhang HY, Zhang JL, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zhao XH, Zheng F, Zhong WJ, Zhou B, Zhou H, Zhou JN, Zhou M, Zhou P, Zhou R, Zhou XX, Zhou XX, Zhu BY, Zhu CG, Zhu FR, Zhu H, Zhu KJ, Zou YC, and Zuo X
Abstract: On 9 October 2022, the Large High Altitude Air Shower Observatory (LHAASO) reported the observation of the very early TeV afterglow of the brightest-of-all-time gamma-ray burst 221009A, recording the highest photon statistics in the TeV band ever obtained from a gamma-ray burst. We use this unique observation to place stringent constraints on the energy dependence of the speed of light in vacuum, a manifestation of Lorentz invariance violation (LIV) predicted by some quantum gravity (QG) theories. Our results show that the 95% confidence level lower limits on the QG energy scales are E_{QG,1}>10 times the Planck energy E_{Pl} for the linear LIV effect, and E_{QG,2}>6×10^{-8}E_{Pl} for the quadratic LIV effect. Our limits on the quadratic LIV case improve previous best bounds by factors of 5-7.
Published: 2024
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44. Constraints on Ultraheavy Dark Matter Properties from Dwarf Spheroidal Galaxies with LHAASO Observations.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai JT, Cao Q, Cao WY, Cao Z, Chang J, Chang JF, Chen AM, Chen ES, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng N, Cheng YD, Cui MY, Cui SW, Cui XH, Cui YD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Dong XQ, Duan KK, Fan JH, Fan YZ, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng XT, Feng YL, Gabici S, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Giacinti G, Gong GH, Gou QB, Gu MH, Guo FL, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He JY, He XB, He Y, Heller M, Hor YK, Hou BW, Hou C, Hou X, Hu HB, Hu Q, Hu SC, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Huang ZC, Ji XL, Jia HY, Jia K, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Ke T, Kuleshov D, Kurinov K, Li BB, Li C, Li C, Li D, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li J, Li K, Li WL, Li WL, Li XR, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Lu R, Luo Q, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Min Z, Mitthumsiri W, Mu HJ, Nan YC, Neronov A, Ou ZW, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Sáiz A, Semikoz D, Shao CY, Shao L, Shchegolev O, Sheng XD, Shu FW, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang QW, Tang ZB, Tian WW, Wang C, Wang CB, Wang GW, Wang HG, Wang HH, Wang JC, Wang K, Wang LP, Wang LY, Wang PH, Wang R, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xin GG, Xin YL, Xing Y, Xiong Z, Xu DL, Xu RF, Xu RX, Xu WL, Xue L, Yan DH, Yan JZ, Yan T, Yang CW, Yang F, Yang FF, Yang HW, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zha M, Zhang BB, Zhang F, Zhang HM, Zhang HY, Zhang JL, Zhang LX, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zhou B, Zhou H, Zhou JN, Zhou M, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, and Zuo X
Abstract: In this Letter we try to search for signals generated by ultraheavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible γ rays by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of the LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter that have low fluxes of astrophysical γ-ray background while having large amount of dark matter. By analyzing more than 700 days of observational data at LHAASO, no significant dark matter signal from 1 TeV to 1 EeV is detected. Accordingly we derive the most stringent constraints on the ultraheavy dark matter annihilation cross section up to EeV. The constraints on the lifetime of dark matter in decay mode are also derived.
Published: 2024
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45. Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A.

Author: Cao Z, Aharonian F, Axikegu, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Bian W, Bukevich AV, Cao Q, Cao WY, Cao Z, Chang J, Chang JF, Chen AM, Chen ES, Chen HX, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen S, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng N, Cheng YD, Cui MY, Cui SW, Cui XH, Cui YD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Dong XQ, Duan KK, Fan JH, Fan YZ, Fang J, Fang JH, Fang K, Feng CF, Feng H, Feng L, Feng SH, Feng XT, Feng Y, Feng YL, Gabici S, Gao B, Gao CD, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Giacinti G, Gong GH, Gou QB, Gu MH, Guo FL, Guo XL, Guo YQ, Guo YY, Han YA, Hasan M, He HH, He HN, He JY, He Y, Hor YK, Hou BW, Hou C, Hou X, Hu HB, Hu Q, Hu SC, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Ji XL, Jia HY, Jia K, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Karpikov I, Kuleshov D, Kurinov K, Li BB, Li CM, Li C, Li C, Li D, Li F, Li HB, Li HC, Li J, Li J, Li K, Li SD, Li WL, Li WL, Li XR, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu DB, Liu H, Liu HD, Liu J, Liu JL, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Luo Q, Luo Y, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Min Z, Mitthumsiri W, Mu HJ, Nan YC, Neronov A, Ou LJ, Pattarakijwanich P, Pei ZY, Qi JC, Qi MY, Qiao BQ, Qin JJ, Raza A, Ruffolo D, Sáiz A, Saeed M, Semikoz D, Shao L, Shchegolev O, Sheng XD, Shu FW, Song HC, Stenkin YV, Stepanov V, Su Y, Sun DX, Sun QN, Sun XN, Sun ZB, Takata J, Tam PHT, Tang QW, Tang R, Tang ZB, Tian WW, Wang C, Wang CB, Wang GW, Wang HG, Wang HH, Wang JC, Wang K, Wang K, Wang LP, Wang LY, Wang PH, Wang R, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu QW, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xiang GM, Xiao DX, Xiao G, Xin YL, Xing Y, Xiong DR, Xiong Z, Xu DL, Xu RF, Xu RX, Xu WL, Xue L, Yan DH, Yan JZ, Yan T, Yang CW, Yang CY, Yang F, Yang FF, Yang LL, Yang MJ, Yang RZ, Yang WX, Yao YH, Yao ZG, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zha M, Zhang BB, Zhang F, Zhang H, Zhang HM, Zhang HY, Zhang JL, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zhao XH, Zheng F, Zhong WJ, Zhou B, Zhou H, Zhou JN, Zhou M, Zhou P, Zhou R, Zhou XX, Zhou XX, Zhu BY, Zhu CG, Zhu FR, Zhu H, Zhu KJ, Zou YC, and Zuo X
Abstract: We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15 PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.
Published: 2024
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46. Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai JT, Cao Q, Cao WY, Cao Z, Chang J, Chang JF, Chen AM, Chen ES, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng N, Cheng YD, Cui MY, Cui SW, Cui XH, Cui YD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Dong XQ, Duan KK, Fan JH, Fan YZ, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng XT, Feng YL, Gabici S, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Giacinti G, Gong GH, Gou QB, Gu MH, Guo FL, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He JY, He XB, He Y, Heller M, Hor YK, Hou BW, Hou C, Hou X, Hu HB, Hu Q, Hu SC, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Huang ZC, Ji XL, Jia HY, Jia K, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Ke T, Kuleshov D, Kurinov K, Li BB, Li C, Li C, Li D, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li J, Li K, Li WL, Li WL, Li XR, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Lu R, Luo Q, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Min Z, Mitthumsiri W, Mu HJ, Nan YC, Neronov A, Ou ZW, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Sáiz A, Semikoz D, Shao CY, Shao L, Shchegolev O, Sheng XD, Shu FW, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang QW, Tang ZB, Tian WW, Wang C, Wang CB, Wang GW, Wang HG, Wang HH, Wang JC, Wang K, Wang LP, Wang LY, Wang PH, Wang R, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xin GG, Xin YL, Xing Y, Xiong Z, Xu DL, Xu RF, Xu RX, Xu WL, Xue L, Yan DH, Yan JZ, Yan T, Yang CW, Yang F, Yang FF, Yang HW, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zha M, Zhang BB, Zhang F, Zhang HM, Zhang HY, Zhang JL, Zhang LX, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zhou B, Zhou H, Zhou JN, Zhou M, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, and Zuo X
Abstract: The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10 TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60 TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.
Published: 2023
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47. A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai LX, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai JT, Cao Q, Cao WY, Cao Z, Chang J, Chang JF, Chen ES, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng HL, Cheng N, Cheng YD, Cui SW, Cui XH, Cui YD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Dong XQ, Duan KK, Fan JH, Fan YZ, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng XT, Feng YL, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Gong GH, Gou QB, Gu MH, Guo FL, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He JY, He XB, He Y, Heller M, Hor YK, Hou BW, Hou C, Hou X, Hu HB, Hu Q, Hu SC, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Huang ZC, Ji XL, Jia HY, Jia K, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Ke T, Kuleshov D, Kurinov K, Li BB, Li C, Li C, Li D, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li J, Li K, Li WL, Li WL, Li XR, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JL, Liu JS, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Long WJ, Lu R, Luo Q, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Min Z, Mitthumsiri W, Nan YC, Ou ZW, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Sáiz A, Shao CY, Shao L, Shchegolev O, Sheng XD, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang ZB, Tian WW, Wang C, Wang CB, Wang GW, Wang HG, Wang HH, Wang JC, Wang JS, Wang K, Wang LP, Wang LY, Wang PH, Wang R, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xin GG, Xin YL, Xing Y, Xiong Z, Xu DL, Xu RF, Xu RX, Xue L, Yan DH, Yan JZ, Yan T, Yang CW, Yang F, Yang FF, Yang HW, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zeng ZK, Zha M, Zhang B, Zhang BB, Zhang F, Zhang HM, Zhang HY, Zhang JL, Zhang LX, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zheng JH, Zhou B, Zhou H, Zhou JN, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, and Zuo X
Abstract: Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory (LHAASO) of the bright GRB 221009A, which serendipitously occurred within the instrument's field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger and then rose to a peak ~10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle of ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.
Published: 2023
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48. Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai LX, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai JT, Cao Z, Chang J, Chang JF, Chen ES, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen Y, Cheng HL, Cheng N, Cheng YD, Cui SW, Cui XH, Cui YD, D'Ettorre Piazzoli B, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Duan KK, Fan JH, Fan YZ, Fan ZX, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng XT, Feng YL, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Gao WK, Ge MM, Geng LS, Gong GH, Gou QB, Gu MH, Guo FL, Guo JG, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He SL, He XB, He Y, Heller M, Hor YK, Hou C, Hou X, Hu HB, Hu Q, Hu S, Hu SC, Hu XJ, Huang DH, Huang WH, Huang XT, Huang XY, Huang Y, Huang ZC, Ji XL, Jia HY, Jia K, Jiang K, Jiang ZJ, Jin M, Kang MM, Ke T, Kuleshov D, Levochkin K, Li BB, Li C, Li C, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li J, Li K, Li WL, Li XR, Li X, Li X, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JS, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Long WJ, Lu R, Luo Q, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Masood A, Min Z, Mitthumsiri W, Nan YC, Ou ZW, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Sáiz A, Shao CY, Shao L, Shchegolev O, Sheng XD, Shi JY, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang ZB, Tian WW, Wang BD, Wang C, Wang H, Wang HG, Wang JC, Wang JS, Wang LP, Wang LY, Wang R, Wang RN, Wang W, Wang XG, Wang XY, Wang Y, Wang YD, Wang YJ, Wang YP, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu XF, Wu YS, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xin GG, Xin YL, Xing Y, Xiong Z, Xu DL, Xu RX, Xue L, Yan DH, Yan JZ, Yang CW, Yang FF, Yang HW, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Yue H, Zeng HD, Zeng TX, Zeng W, Zeng ZK, Zha M, Zhai XX, Zhang BB, Zhang F, Zhang HM, Zhang HY, Zhang JL, Zhang LX, Zhang L, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SB, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang YL, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zheng Y, Zhou B, Zhou H, Zhou JN, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, Zuo X, Ando S, Chianese M, Fiorillo DFG, Miele G, and Ng KCY
Abstract: The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9} GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.
Published: 2022
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49. Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai LX, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai H, Cai JT, Cao Z, Chang J, Chang JF, Chen BM, Chen ES, Chen J, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen XL, Chen Y, Cheng N, Cheng YD, Cui SW, Cui XH, Cui YD, Piazzoli BD, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Dong XJ, Duan KK, Fan JH, Fan YZ, Fan ZX, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng YL, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Ge MM, Geng LS, Gong GH, Gou QB, Gu MH, Guo FL, Guo JG, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He JC, He SL, He XB, He Y, Heller M, Hor YK, Hou C, Hou X, Hu HB, Hu S, Hu SC, Hu XJ, Huang DH, Huang QL, Huang WH, Huang XT, Huang XY, Huang ZC, Ji F, Ji XL, Jia HY, Jiang K, Jiang ZJ, Jin C, Ke T, Kuleshov D, Levochkin K, Li BB, Li C, Li C, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li K, Li WL, Li XR, Li X, Li X, Li Y, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JS, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Liu ZX, Long WJ, Lu R, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Masood A, Min Z, Mitthumsiri W, Montaruli T, Nan YC, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Rulev V, Sáiz A, Shao L, Shchegolev O, Sheng XD, Shi JR, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang ZB, Tian WW, Wang BD, Wang C, Wang H, Wang HG, Wang JC, Wang JS, Wang LP, Wang LY, Wang RN, Wang W, Wang W, Wang XG, Wang XJ, Wang XY, Wang Y, Wang YD, Wang YJ, Wang YP, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu WX, Wu XF, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xiao HB, Xin GG, Xin YL, Xing Y, Xu DL, Xu RX, Xue L, Yan DH, Yan JZ, Yang CW, Yang FF, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Zeng HD, Zeng TX, Zeng W, Zeng ZK, Zha M, Zhai XX, Zhang BB, Zhang HM, Zhang HY, Zhang JL, Zhang JW, Zhang LX, Zhang L, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang YL, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zheng Y, Zhou B, Zhou H, Zhou JN, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, and Zuo X
Abstract: Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.
Published: 2022
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50. Peta-electron volt gamma-ray emission from the Crab Nebula.

Author: Cao Z, Aharonian F, An Q, Axikegu, Bai LX, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai H, Cai JT, Cao Z, Chang J, Chang JF, Chen BM, Chen ES, Chen J, Chen L, Chen L, Chen L, Chen MJ, Chen ML, Chen QH, Chen SH, Chen SZ, Chen TL, Chen XL, Chen Y, Cheng N, Cheng YD, Cui SW, Cui XH, Cui YD, D'Ettorre Piazzoli B, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, Dong XJ, Duan KK, Fan JH, Fan YZ, Fan ZX, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng YL, Gao B, Gao CD, Gao LQ, Gao Q, Gao W, Ge MM, Geng LS, Gong GH, Gou QB, Gu MH, Guo FL, Guo JG, Guo XL, Guo YQ, Guo YY, Han YA, He HH, He HN, He JC, He SL, He XB, He Y, Heller M, Hor YK, Hou C, Hou X, Hu HB, Hu S, Hu SC, Hu XJ, Huang DH, Huang QL, Huang WH, Huang XT, Huang XY, Huang ZC, Ji F, Ji XL, Jia HY, Jiang K, Jiang ZJ, Jin C, Ke T, Kuleshov D, Levochkin K, Li BB, Li C, Li C, Li F, Li HB, Li HC, Li HY, Li J, Li J, Li K, Li WL, Li XR, Li X, Li X, Li Y, Li YZ, Li Z, Li Z, Liang EW, Liang YF, Lin SJ, Liu B, Liu C, Liu D, Liu H, Liu HD, Liu J, Liu JL, Liu JS, Liu JY, Liu MY, Liu RY, Liu SM, Liu W, Liu Y, Liu YN, Liu ZX, Long WJ, Lu R, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Masood A, Min Z, Mitthumsiri W, Montaruli T, Nan YC, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Qi YQ, Qiao BQ, Qin JJ, Ruffolo D, Rulev V, Saiz A, Shao L, Shchegolev O, Sheng XD, Shi JY, Song HC, Stenkin YV, Stepanov V, Su Y, Sun QN, Sun XN, Sun ZB, Tam PHT, Tang ZB, Tian WW, Wang BD, Wang C, Wang H, Wang HG, Wang JC, Wang JS, Wang LP, Wang LY, Wang RN, Wang W, Wang W, Wang XG, Wang XJ, Wang XY, Wang Y, Wang YD, Wang YJ, Wang YP, Wang ZH, Wang ZX, Wang Z, Wang Z, Wei DM, Wei JJ, Wei YJ, Wen T, Wu CY, Wu HR, Wu S, Wu WX, Wu XF, Xi SQ, Xia J, Xia JJ, Xiang GM, Xiao DX, Xiao G, Xiao HB, Xin GG, Xin YL, Xing Y, Xu DL, Xu RX, Xue L, Yan DH, Yan JZ, Yang CW, Yang FF, Yang JY, Yang LL, Yang MJ, Yang RZ, Yang SB, Yao YH, Yao ZG, Ye YM, Yin LQ, Yin N, You XH, You ZY, Yu YH, Yuan Q, Zeng HD, Zeng TX, Zeng W, Zeng ZK, Zha M, Zhai XX, Zhang BB, Zhang HM, Zhang HY, Zhang JL, Zhang JW, Zhang LX, Zhang L, Zhang L, Zhang PF, Zhang PP, Zhang R, Zhang SR, Zhang SS, Zhang X, Zhang XP, Zhang YF, Zhang YL, Zhang Y, Zhang Y, Zhao B, Zhao J, Zhao L, Zhao LZ, Zhao SP, Zheng F, Zheng Y, Zhou B, Zhou H, Zhou JN, Zhou P, Zhou R, Zhou XX, Zhu CG, Zhu FR, Zhu H, Zhu KJ, and Zuo X
Abstract: The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10 -4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10 36 ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
Published: 2021
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