Cao Z.Aharonian F.Bai Y.X.Bao Y.W.Bastieri D.Bi X.J.Bi Y.J.Bian W.Bukevich A.V.Cai C.M.Cao W.Y.Cao Z.Chang J.Chang J.F.Chen A.M.Chen E.S.Chen G.H.Chen H.X.Chen L.Chen L.Chen M.J.Chen M.L.Chen Q.H.Chen S.Chen S.H.Chen S.Z.Chen T.L.Chen X.B.Chen X.J.Chen Y.Cheng N.Cheng Y.D.Chu M.C.Cui M.Y.Cui S.W.Cui X.H.Cui Y.D.Dai B.Z.Dai H.L.Dai Z.G.DanzengluobuDiao Y.X.Dong X.Q.Duan K.K.Fan J.H.Fan Y.Z.Fang J.Fang J.H.Fang K.Feng C.F.Feng H.Feng L.Feng S.H.Feng X.T.Feng Y.Feng Y.L.Gabici S.Gao B.Gao C.D.Gao Q.Gao W.Gao W.K.Ge M.M.Ge T.T.Geng L.S.Giacinti G.Gong G.H.Gou Q.B.Gu M.H.Guo F.L.Guo J.Guo X.L.Guo Y.Q.Guo Y.Y.Han Y.A.Hannuksela O.A.Hasan M.He H.H.He H.N.He J.Y.He X.Y.He Y.Hernández-Cadena S.Hou B.W.Hou C.Hou X.Hu H.B.Hu S.C.Huang C.Huang D.H.Huang J.J.Huang T.Q.Huang W.J.Huang X.T.Huang X.Y.Huang Y.Huang Y.Y.Ji X.L.Jia H.Y.Jia K.Mahidol University2026-02-082026-02-082025-12-30Proceedings of Science Vol.501 (2025)https://repository.li.mahidol.ac.th/handle/123456789/114905CTB 109 is a middle-aged shell-type supernova remnant (SNR) with bright thermal X-ray emission. The gamma-ray emission of CTB 109 exhibits a center-bright morphology, which is very consistent with its thermal X-ray emission rather than the shell-type structure in the radio band. The GeV gamma-ray spectrum shows a significant spectral curvature at a few GeV, which can well explain the lack of TeV gamma-ray emission from CTB 109. In this work, we describe the observations of CTB 109 by LHAASO, together with the updated observations by Fermi-LAT. Based on the LHAASO measurements, we will set stringent upper limits on the distribution of particles accelerated by CTB 109. We perform extensive modelling using multi-wavelength data available for CTB 109, and discuss the different emission models for leptonic and hadronic scenarios.MultidisciplinaryConference PaperSCOPUS10.22323/1.501.07322-s2.0-10502904969118248039