Cao Zhen, Aharonian F, An Q, Bai Y X, Bao Y W, Bastieri D, Bi X J, Bi Y J, Cai J T, Cao Q, Cao W Y, Cao Zhe, Chang J, Chang J F, Chen 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, Cheng N, Cheng Y D, Cui M Y, Cui S W, Cui X H, Cui Y D, Dai B Z, Dai H L, Dai Z G, Della Volpe D, Dong X Q, Duan K K, Fan J H, Fan Y Z, Fang J, Fang K, Feng C F, Feng L, Feng S H, Feng X T, Feng Y L, Gabici S, Gao B, Gao C D, Gao L Q, Gao Q, Gao W, Gao W K, Ge M M, Geng L S, Giacinti G, Gong G H, Gou Q B, Gu M H, Guo F L, Guo X L, Guo Y Q, Guo Y Y, Han Y A, He H H, He H N, He J Y, He X B, He Y, Heller M, Hor Y K, Hou B W, Hou C, Hou X, Hu H B, Hu Q, Hu S C, Huang D H, Huang T Q, Huang W J, Huang X T, Huang X Y, Huang Y, Huang Z C, Ji X L, Jia H Y, Jia K, Jiang K, Jiang X W, Jiang Z J, Jin M, Kang M M, Ke T, Kuleshov D, Kurinov K, Li 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 W L, Li X R, Li Xin, Li Y Z, Li Zhe, Li Zhuo, Liang E W, Liang Y F, Lin S J, Liu 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, Lu R, Luo Q, Lv H K, Ma B Q, Ma L L, Ma X H, Mao J R, Min Z, Mitthumsiri W, Mu H J, Nan Y C, Neronov A, Ou Z W, Pang B Y, Pattarakijwanich P, Pei Z Y, Qi M Y, Qi Y Q, Qiao B Q, Qin J J, Ruffolo D, Sáiz A, Semikoz D, Shao C Y, Shao L, Shchegolev O, Sheng X D, Shu F W, Song H C, Stenkin Yu V, Stepanov V, Su Y, Sun Q N, Sun X N, Sun Z B, Tam P H T, Tang Q W, Tang Z B, Tian W W, Wang 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, Wei D M, Wei J J, Wei Y J, Wen T, Wu C Y, Wu H R, Wu S, Wu X F, Wu Y S, Xi S Q, Xia J, Xia J J, Xiang G M, Xiao D X, Xiao G, Xin G G, Xin Y L, Xing Y, Xiong Z, Xu D L, Xu R F, Xu R X, Xu W L, Xue L, Yan D H, Yan J Z, Yan T, Yang 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, Yao Y H, Yao Z G, Ye Y M, Yin L Q, Yin N, You X H, You Z Y, Yu Y H, Yuan Q, Yue H, Zeng H D, Zeng T X, Zeng W, Zha M, Zhang 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, Zhao B, Zhao J, Zhao L, Zhao L Z, Zhao S P, Zheng F, Zhou B, Zhou H, Zhou J N, Zhou M, Zhou P, Zhou R, Zhou X X, Zhu C G, Zhu F R, Zhu H, Zhu K J, Zuo X
Key Laboratory of Particle Astrophyics & Experimental Physics Division & Computing Center, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing, China.
University of Chinese Academy of Sciences, 100049 Beijing, China.
Phys Rev Lett. 2023 Oct 13;131(15):151001. doi: 10.1103/PhysRevLett.131.151001.
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°<l<125°, |b|<5°) and outer (125°<l<235°, |b|<5°) Galactic plane are detected with 29.1σ and 12.7σ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain (E>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.
弥漫的银河系γ射线发射主要通过宇宙射线与星际介质和/或辐射场之间的相互作用产生，是探测宇宙射线在银河系中分布、传播和相互作用的非常重要的手段。在本快报中，我们报告了利用大型高海拔空气簇射观测站（LHAASO）的平方公里阵列对银河系平面10 TeV至1 PeV能量之间弥漫γ射线的测量结果。分别以29.1σ和12.7σ的显著性探测到了内（15°<l<125°，|b|<5°）银河系平面和外（125°<l<235°，|b|<5°）银河系平面的弥漫发射。外银河系平面的弥漫发射在甚高能到超高能域（E>10 TeV）首次被探测到。内银河系区域的能谱可用指数为-2.99±0.04的幂律函数来描述，这与局部测量的宇宙射线与视线积分气体含量之间强子相互作用预期的弯曲能谱不同。此外，测量到的通量比预测值高约3倍。在外银河系区域发现了指数为-2.99±0.07的类似能谱，并且在10≲E≲60 TeV范围内的绝对通量再次高于强子宇宙射线相互作用的预测值。弥漫发射的纬度分布与气体分布一致，而经度分布则明显偏离气体分布。LHAASO的测量结果表明，要么存在额外的发射源，要么宇宙射线强度存在空间变化。
