Ajello, M.M.AjelloAlbert, A.A.AlbertAnderson, B.B.AndersonBaldini, L.L.BaldiniBarbiellini, G.G.BarbielliniBastieri, D.D.BastieriBellazzini, R.R.BellazziniBissaldi, E.E.BissaldiBlandford, R. D.R. D.BlandfordBloom, E. D.E. D.BloomBonino, R.R.BoninoBottacini, E.E.BottaciniBregeon, J.J.BregeonBruel, P.P.BruelBuehler, R.R.BuehlerCaliandro, G. A.G. A.CaliandroCameron, R. A.R. A.CameronCaragiulo, M.M.CaragiuloCARAVEO, PATRIZIAPATRIZIACARAVEOCecchi, C.C.CecchiChekhtman, A.A.ChekhtmanCiprini, S.S.CipriniCohen-Tanugi, J.J.Cohen-TanugiConrad, J.J.ConradCostanza, F.F.CostanzaD'AMMANDO, FILIPPOFILIPPOD'AMMANDOde Angelis, A.A.de Angelisde Palma, F.F.de PalmaDesiante, R.R.DesianteDi Mauro, M.M.Di MauroDi Venere, L.L.Di VenereDomínguez, A.A.DomínguezDrell, P. S.P. S.DrellFavuzzi, C.C.FavuzziFocke, W. B.W. B.FockeFranckowiak, A.A.FranckowiakFukazawa, Y.Y.FukazawaFunk, S.S.FunkFusco, P.P.FuscoGargano, F.F.GarganoGasparrini, D.D.GasparriniGiglietto, N.N.GigliettoGlanzman, T.T.GlanzmanGodfrey, G.G.GodfreyGuiriec, S.S.GuiriecHoran, D.D.HoranJóhannesson, G.G.JóhannessonKatsuragawa, M.M.KatsuragawaKensei, S.S.KenseiKuss, M.M.KussLarsson, S.S.LarssonLatronico, L.L.LatronicoLi, J.J.LiLi, L.L.LiLongo, F.F.LongoLoparco, F.F.LoparcoLubrano, P.P.LubranoMadejski, G. M.G. M.MadejskiMaldera, S.S.MalderaManfreda, A.A.ManfredaMayer, M.M.MayerMazziotta, M. N.M. N.MazziottaMeyer, M.M.MeyerMichelson, P. F.P. F.MichelsonMirabal, N.N.MirabalMizuno, T.T.MizunoMonzani, M. E.M. E.MonzaniMorselli, A.A.MorselliMoskalenko, I. V.I. V.MoskalenkoMurgia, S.S.MurgiaNegro, M.M.NegroNuss, E.E.NussOkada, C.C.OkadaOrlando, E.E.OrlandoOrmes, J. F.J. F.OrmesPaneque, D.D.PanequePerkins, J. S.J. S.PerkinsPesce-Rollins, M.M.Pesce-RollinsPiron, F.F.PironPivato, G.G.PivatoPorter, T. A.T. A.PorterRainò, S.S.RainòRando, R.R.RandoRazzano, M.M.RazzanoReimer, A.A.ReimerSánchez-Conde, M.M.Sánchez-CondeSgrò, C.C.SgròSimone, D.D.SimoneSiskind, E. J.E. J.SiskindSpada, F.F.SpadaSpandre, G.G.SpandreSpinelli, P.P.SpinelliTakahashi, H.H.TakahashiThayer, J. B.J. B.ThayerTorres, D. F.D. F.TorresTosti, G.G.TostiTroja, E.E.TrojaUchiyama, Y.Y.UchiyamaWood, K. S.K. S.WoodWood, M.M.WoodZaharijas, G.G.ZaharijasZimmer, S.S.ZimmerFermi-LAT Collaboration2020-05-142020-05-1420160031-9007http://hdl.handle.net/20.500.12386/24840We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ -ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 ×10<SUP>-12</SUP> GeV<SUP>-1</SUP> for ALP masses 0.5 ≲m<SUB>a</SUB>≲5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ -ray opacity of the Universe.STAMPAenArticle10.1103/PhysRevLett.116.1611012-s2.0-84964467037000374559300002https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.1611012016PhRvL.116p1101AFIS/05 - ASTRONOMIA E ASTROFISICAScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation