Cao Z.Aharonian F.AxikeguBai Y.X.Bao Y.W.Bastieri D.Bi X.J.Bi Y.J.Bian W.Bukevich A.V.Cao Q.Cao W.Y.Cao Z.Chang J.Chang J.F.Chen A.M.Chen E.S.Chen H.X.Chen L.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 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.DanzengluobuDong 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 Y.Hor Y.K.Hou B.W.Hou C.Hou X.Hu H.B.Hu Q.Hu S.C.Huang C.Huang D.H.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.Jiang H.B.Jiang K.Jiang X.W.Mahidol University2025-02-182025-02-182025-07-01Science China: Physics, Mechanics and Astronomy Vol.68 No.7 (2025)16747348https://repository.li.mahidol.ac.th/handle/20.500.14594/105350We report the detection of an extended very-high-energy (VHE) γ-ray source coincident with the location of middle-aged (62.4 kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 d and LHAASO-KM2A data of live 1216 d. A significant excess of γ-ray induced showers is observed both by WCDA in energy bands of 1–25 TeV and KM2A in energy bands of >25 TeV with 7.3σ and 13.5σ, respectively. The best-fit position derived through WCDA data is R.A. = 42.06° ± 0.12° and Dec. = 60.24° ± 0.13° with an extension of 0.69°±0.15° and that of the KM2A data is R.A.= 42.29° ± 0.13° and Dec. = 60.38° ± 0.07° with an extension of 0.37° ±0.07°. No clear extended multiwavelength counterpart of this LHAASO source has been found from the radio band to the GeV band. The most plausible explanation of the VHE γ-ray emission is the inverse Compton process of highly relativistic electrons and positrons injected by the pulsar. These electrons/positrons are hypothesized to be either confined within the pulsar wind nebula or to have already escaped into the interstellar medium, forming a pulsar halo.Physics and AstronomyArticleSCOPUS10.1007/s11433-024-2508-52-s2.0-8521755993418691927