2026-05-07 中国科学院（CAS）
Broadband energy spectrum measurement of the gamma-ray binary LS I +61° 303. (Image by the LHAASO Collaboration)
＜関連情報＞
- https://english.cas.cn/newsroom/research-news/202604/t20260424_1157922.shtml
- https://journals.aps.org/prl/abstract/10.1103/7xhp-tff7
ガンマ線連星LS Iからの超高エネルギー放射の初検出+61°303 First Detection of Ultrahigh Energy Emission from Gamma-Ray Binary LS I +61° 303
Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, A. V. Bukevich et al. (LHAASO Collaboration)
Physical Review Letters Published: 6 May, 2026
DOI: https://doi.org/10.1103/7xhp-tff7
Abstract
We report the first detection of gamma-ray emission up to ultrahigh-energy (UHE; >100 TeV) emission from the prototypical gamma-ray binary system LS I +61° 303 using data from the Large High Altitude Air Shower Observatory. It is detected with significances of 9.2δ in the Water Cherenkov Detector Array (WCDA, 1.4−30.5 TeV) and 6.2δ in the Kilometer Square Array (KM2A, 25−267 TeV); in KM2A alone we identify 16 photonlike events above 100 TeV against an estimated 5.1 background events, corresponding to a 3.8δ detection. These results provide compelling evidence of extreme particle acceleration in LS I +61° 303. Furthermore, we observe orbital modulation at 3.9δ confidence level, between 25 and 100 TeV, with a hint that the orbital modulation is energy dependent. These features can be understood in a composite scenario in which leptonic and hadronic processes jointly contribute.
