M. AckermannM. AjelloL. BaldiniJ. BalletG. BarbielliniD. BastieriR. BellazziniE. BissaldiR. D. BlandfordE. D. BloomR. BoninoT. J. BrandtJ. BregeonP. BruelR. BuehlerS. BusonG. A. CaliandroR. A. CameronM. CaragiuloP. A. CaraveoE. CavazzutiC. CecchiE. CharlesA. ChekhtmanC. C. CheungG. ChiaroS. CipriniJ. M. CohenJ. Cohen-TanugiF. CostanzaS. CutiniF. D'AmmandoD. S. DavisA. De AngelisF. De PalmaR. DesianteS. W. DigelN. Di LallaM. Di MauroL. Di VenereC. FavuzziS. J. FeganE. C. FerraraW. B. FockeY. FukazawaS. FunkP. FuscoF. GarganoD. GasparriniM. GeorganopoulosN. GigliettoF. GiordanoM. GirolettiG. GodfreyD. GreenI. A. GrenierS. GuiriecE. HaysJ. W. HewittA. B. HillT. JoglerG. JóhannessonS. KenseiM. KussS. LarssonL. LatronicoJ. LiL. LiF. LongoF. LoparcoP. LubranoDeutsche Elektronen-SynchrotronClemson UniversityUniversità di PisaKavli Institute for Particle Astrophysics and CosmologyInstitut de Recherche sur les Lois Fondamentales de l'UniversIstituto Nazionale di Fisica Nucleare, RomaUniversita degli Studi di TriesteIstituto Nazionale Di Fisica Nucleare, Sezione di PadovaUniversità degli Studi di PadovaIstituto Nazionale Di Fisica Nucleare, Sezione di PisaUniversità degli Studi di TorinoNASA Goddard Space Flight CenterLaboratoire Univers et Particules de MontpellierLaboratoire Leprince-RinguetUniversity of Maryland, Baltimore CountyConsorzio Interuniversitario per la Fisica Spaziale (CIFS)Università degli Studi di BariINAF Istituto di Astrofisica Spaziale e Fisica Cosmica, MilanAgenzia Spaziale ItalianaUniversita degli Studi di PerugiaGeorge Mason University, Fairfax CampusNaval Research LaboratoryUniversity of MarylandIstituto Di Radioastronomia, BolognaAlma Mater Studiorum Università di BolognaUniversita degli Studi di UdineUniversità degli Studi di Napoli Federico IIHiroshima UniversityErlangen Centre for Astroparticle PhysicsUniversity of North FloridaUniversity of SouthamptonUniversity Science Institute ReykjavikThe Royal Institute of Technology (KTH)Oskar Klein Centre for Cosmoparticle PhysicsUniversitat Autònoma de BarcelonaMahidol UniversityUniversity of California, IrvineUniversity of DenverMax Planck Institut fur Physik (Werner-Heisenberg-Institut)2018-12-112019-03-142018-12-112019-03-142016-07-20Astrophysical Journal. Vol.826, No.1 (2016)153843570004637X2-s2.0-84979233553https://repository.li.mahidol.ac.th/handle/20.500.14594/43561© 2016. The American Astronomical Society. All rights reserved. We report the Fermi Large Area Telescope detection of extended γ-ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ-ray source attributed to a radio galaxy. Both an extended flat disk morphology and a morphology following the extended radio lobes were preferred over a point-source description, and the core contribution was constrained to be % of the total γ-ray flux. A preferred alignment of the γ-ray elongation with the radio lobes was demonstrated by rotating the radio lobes template. We found no significant evidence for variability on ∼0.5 year timescales. Taken together, these results strongly suggest a lobe origin for the γ-rays. With the extended nature of the γ-ray emission established, we model the source broadband emission considering currently available total lobe radio and millimeter flux measurements, as well as X-ray detections attributed to inverse Compton (IC) emission off the cosmic microwave background (CMB). Unlike the Centaurus A case, we find that a leptonic model involving IC scattering of CMB and extragalactic background light (EBL) photons underpredicts the γ-ray fluxes by factors of about ∼2-3, depending on the EBL model adopted. An additional γ-ray spectral component is thus required, and could be due to hadronic emission arising from proton-proton collisions of cosmic rays with thermal plasma within the radio lobes.Mahidol UniversityEarth and Planetary SciencesArticleSCOPUS10.3847/0004-637X/826/1/1