Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Oct 13;131(15):151001.
doi: 10.1103/PhysRevLett.131.151001.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

Zhen Cao  1   2   3 , F Aharonian  4   5 , Q An  6   7 , Axikegu  8 , Y X Bai  1   3 , Y W Bao  9 , D Bastieri  10 , X J Bi  1   2   3 , Y J Bi  1   3 , J T Cai  10 , Q Cao  11 , W Y Cao  7 , Zhe Cao  6   7 , J Chang  12 , J F Chang  1   3   6 , A M Chen  13 , E S Chen  1   2   3 , Liang Chen  14 , Lin Chen  8 , Long Chen  8 , M J Chen  1   3 , M L Chen  1   3   6 , Q H Chen  8 , S H Chen  1   2   3 , S Z Chen  1   3 , T L Chen  15 , Y Chen  9 , N Cheng  1   3 , Y D Cheng  1   3 , M Y Cui  12 , S W Cui  11 , X H Cui  16 , Y D Cui  17 , B Z Dai  18 , H L Dai  1   3   6 , Z G Dai  7 , Danzengluobu  15 , D Della Volpe  19 , X Q Dong  1   2   3 , K K Duan  12 , J H Fan  10 , Y Z Fan  12 , J Fang  18 , K Fang  1   3 , C F Feng  20 , L Feng  12 , S H Feng  1   3 , X T Feng  20 , Y L Feng  15 , S Gabici  21 , B Gao  1   3 , C D Gao  20 , L Q Gao  1   2   3 , Q Gao  15 , W Gao  1   3 , W K Gao  1   2   3 , M M Ge  18 , L S Geng  1   3 , G Giacinti  13 , G H Gong  22 , Q B Gou  1   3 , M H Gu  1   3   6 , F L Guo  14 , X L Guo  8 , Y Q Guo  1   3 , Y Y Guo  12 , Y A Han  23 , H H He  1   2   3 , H N He  12 , J Y He  12 , X B He  17 , Y He  8 , M Heller  19 , Y K Hor  17 , B W Hou  1   2   3 , C Hou  1   3 , X Hou  24 , H B Hu  1   2   3 , Q Hu  7   12 , S C Hu  1   2   3 , D H Huang  8 , T Q Huang  1   3 , W J Huang  17 , X T Huang  20 , X Y Huang  12 , Y Huang  1   2   3 , Z C Huang  8 , X L Ji  1   3   6 , H Y Jia  8 , K Jia  20 , K Jiang  6   7 , X W Jiang  1   3 , Z J Jiang  18 , M Jin  8 , M M Kang  25 , T Ke  1   3 , D Kuleshov  26 , K Kurinov  26 , B B Li  11 , Cheng Li  6   7 , Cong Li  1   3 , D Li  1   2   3 , F Li  1   3   6 , H B Li  1   3 , H C Li  1   3 , H Y Li  7   12 , J Li  7   12 , Jian Li  7 , Jie Li  1   3   6 , K Li  1   3 , W L Li  20 , W L Li  13 , X R Li  1   3 , Xin Li  6   7 , Y Z Li  1   2   3 , Zhe Li  1   3 , Zhuo Li  27 , E W Liang  28 , Y F Liang  28 , S J Lin  17 , B Liu  7 , C Liu  1   3 , D Liu  20 , H Liu  8 , H D Liu  23 , J Liu  1   3 , J L Liu  1   3 , J Y Liu  1   3 , M Y Liu  15 , R Y Liu  9 , S M Liu  8 , W Liu  1   3 , Y Liu  10 , Y N Liu  22 , R Lu  18 , Q Luo  17 , H K Lv  1   3 , B Q Ma  27 , L L Ma  1   3 , X H Ma  1   3 , J R Mao  24 , Z Min  1   3 , W Mitthumsiri  29 , H J Mu  23 , Y C Nan  1   3 , A Neronov  21 , Z W Ou  17 , B Y Pang  8 , P Pattarakijwanich  29 , Z Y Pei  10 , M Y Qi  1   3 , Y Q Qi  11 , B Q Qiao  1   3 , J J Qin  7 , D Ruffolo  29 , A Sáiz  29 , D Semikoz  21 , C Y Shao  17 , L Shao  11 , O Shchegolev  26   30 , X D Sheng  1   3 , F W Shu  31 , H C Song  27 , Yu V Stenkin  26   30 , V Stepanov  26 , Y Su  12 , Q N Sun  8 , X N Sun  28 , Z B Sun  32 , P H T Tam  17 , Q W Tang  31 , Z B Tang  6   7 , W W Tian  2   16 , C Wang  32 , C B Wang  8 , G W Wang  7 , H G Wang  10 , H H Wang  17 , J C Wang  24 , K Wang  9 , L P Wang  20 , L Y Wang  1   3 , P H Wang  8 , R Wang  20 , W Wang  17 , X G Wang  28 , X Y Wang  9 , Y Wang  8 , Y D Wang  1   3 , Y J Wang  1   3 , Z H Wang  25 , Z X Wang  18 , Zhen Wang  13 , Zheng Wang  1   3   6 , D M Wei  12 , J J Wei  12 , Y J Wei  1   2   3 , T Wen  18 , C Y Wu  1   3 , H R Wu  1   3 , S Wu  1   3 , X F Wu  12 , Y S Wu  7 , S Q Xi  1   3 , J Xia  7   12 , J J Xia  8 , G M Xiang  2   14 , D X Xiao  11 , G Xiao  1   3 , G G Xin  1   3 , Y L Xin  8 , Y Xing  14 , Z Xiong  1   2   3 , D L Xu  13 , R F Xu  1   2   3 , R X Xu  27 , W L Xu  25 , L Xue  20 , D H Yan  18 , J Z Yan  12 , T Yan  1   3 , C W Yang  25 , F Yang  11 , F F Yang  1   3   6 , H W Yang  17 , J Y Yang  17 , L L Yang  17 , M J Yang  1   3 , R Z Yang  7 , S B Yang  18 , Y H Yao  25 , Z G Yao  1   3 , Y M Ye  22 , L Q Yin  1   3 , N Yin  20 , X H You  1   3 , Z Y You  1   2   3 , Y H Yu  7 , Q Yuan  12 , H Yue  1   2   3 , H D Zeng  12 , T X Zeng  1   3   6 , W Zeng  18 , M Zha  1   3 , B B Zhang  9 , F Zhang  8 , H M Zhang  9 , H Y Zhang  1   3 , J L Zhang  16 , L X Zhang  10 , Li Zhang  18 , P F Zhang  18 , P P Zhang  7   12 , R Zhang  7   12 , S B Zhang  2   16 , S R Zhang  11 , S S Zhang  1   3 , X Zhang  9 , X P Zhang  1   3 , Y F Zhang  8 , Yi Zhang  1   12 , Yong Zhang  1   3 , B Zhao  8 , J Zhao  1   3 , L Zhao  6   7 , L Z Zhao  11 , S P Zhao  12   20 , F Zheng  32 , B Zhou  1   3 , H Zhou  13 , J N Zhou  14 , M Zhou  31 , P Zhou  9 , R Zhou  25 , X X Zhou  8 , C G Zhu  20 , F R Zhu  8 , H Zhu  16 , K J Zhu  1   2   3   6 , X Zuo  1   3 ; LHAASO Collaboration
Affiliations

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

Zhen Cao et al. Phys Rev Lett. .

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°<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.

PubMed Disclaimer

Similar articles

  • Measurement of Very-High-Energy Diffuse Gamma-Ray Emissions from the Galactic Plane with LHAASO-WCDA.
    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, Chu MC, 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, Ge TT, Geng LS, Giacinti G, Gong GH, Gou QB, Gu MH, Guo FL, Guo J, Guo XL, Guo YQ, Guo YY, Han YA, Hannuksela OA, 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 C, Huang DH, Huang TQ, Huang WJ, Huang XT, Huang XY, Huang Y, Huang YY, Ji XL, Jia HY, Jia K, Jiang HB, Jiang K, Jiang XW, Jiang ZJ, Jin M, Kang MM, Karpikov I, Khangulyan D, 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, L… See abstract for full author list ➔ Cao Z, et al. Phys Rev Lett. 2025 Feb 28;134(8):081002. doi: 10.1103/PhysRevLett.134.081002. Phys Rev Lett. 2025. PMID: 40085904
  • First Detection of sub-PeV Diffuse Gamma Rays from the Galactic Disk: Evidence for Ubiquitous Galactic Cosmic Rays beyond PeV Energies.
    Amenomori M, Bao YW, Bi XJ, Chen D, Chen TL, Chen WY, Chen X, Chen Y, Cirennima, Cui SW, Danzengluobu, Ding LK, Fang JH, Fang K, Feng CF, Feng Z, Feng ZY, Gao Q, Gou QB, Guo YQ, Guo YY, He HH, He ZT, Hibino K, Hotta N, Hu H, Hu HB, Huang J, Jia HY, Jiang L, Jin HB, Kasahara K, Katayose Y, Kato C, Kato S, Kawata K, Kihara W, Ko Y, Kozai M, Labaciren, Le GM, Li AF, Li HJ, Li WJ, Lin YH, Liu B, Liu C, Liu JS, Liu MY, Liu W, Lou YQ, Lu H, Meng XR, Munakata K, Nakada H, Nakamura Y, Nanjo H, Nishizawa M, Ohnishi M, Ohura T, Ozawa S, Qian XL, Qu XB, Saito T, Sakata M, Sako TK, Shao J, Shibata M, Shiomi A, Sugimoto H, Takano W, Takita M, Tan YH, Tateyama N, Torii S, Tsuchiya H, Udo S, Wang H, Wu HR, Xue L, Yamamoto Y, Yang Z, Yokoe Y, Yuan AF, Zhai LM, Zhang HM, Zhang JL, Zhang X, Zhang XY, Zhang Y, Zhang Y, Zhang Y, Zhao SP, Zhaxisangzhu, Zhou XX; Tibet <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AS</mi></mrow><mrow><mi>γ</mi></mrow></msub></mrow></math> Collaboration. Amenomori M, et al. Phys Rev Lett. 2021 Apr 9;126(14):141101. doi: 10.1103/PhysRevLett.126.141101. Phys Rev Lett. 2021. PMID: 33891464
  • Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A.
    Aharonian F, An Q, Axikegu, Bai LX, Bai YX, Bao YW, Bastieri D, Bi XJ, Bi YJ, Cai H, Cai JT, Cao Z, Cao Z, Chang J, Chang JF, Chang XC, Chen BM, 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, Dai BZ, Dai HL, Dai ZG, Danzengluobu, Della Volpe D, D'Ettorre Piazzoli B, Dong XJ, Fan JH, Fan YZ, Fan ZX, Fang J, Fang K, Feng CF, Feng L, Feng SH, Feng YL, Gao B, Gao CD, Gao Q, Gao W, Ge MM, Geng LS, Gong GH, Gou QB, Gu MH, 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 ZC, Ji F, Ji XL, Jia HY, Jiang K, Jiang ZJ, Jin C, Kuleshov D, Levochkin K, Li BB, Li C, Li C, Li F, Li HB, Li HC, Li HY, Li J, Li K, Li WL, Li X, Li X, Li XR, 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 YN, Liu ZX, Long WJ, Lu R, Lv HK, Ma BQ, Ma LL, Ma XH, Mao JR, Masood A, Mitthumsiri W, Montaruli T, Nan YC, Pang BY, Pattarakijwanich P, Pei ZY, Qi MY, Ruffolo D, Rulev V, Sáiz A… See abstract for full author list ➔ Aharonian F, et al. Phys Rev Lett. 2021 Jun 18;126(24):241103. doi: 10.1103/PhysRevLett.126.241103. Phys Rev Lett. 2021. PMID: 34213924
  • Extragalactic background light measurements and applications.
    Cooray A. Cooray A. R Soc Open Sci. 2016 Mar 9;3(3):150555. doi: 10.1098/rsos.150555. eCollection 2016 Mar. R Soc Open Sci. 2016. PMID: 27069645 Free PMC article. Review.
  • Cosmic ray feedback in galaxies and galaxy clusters: A pedagogical introduction and a topical review of the acceleration, transport, observables, and dynamical impact of cosmic rays.
    Ruszkowski M, Pfrommer C. Ruszkowski M, et al. Astron Astrophys Rev. 2023;31(1):4. doi: 10.1007/s00159-023-00149-2. Epub 2023 Dec 5. Astron Astrophys Rev. 2023. PMID: 38115816 Free PMC article. Review.
See all similar articles

LinkOut - more resources