MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE
M. AckermannDeutsches Elektronen Synchrotron DESY, D-15738 Zeuthen, GermanyRichard AnantuaW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAKatsuaki AsanoInstitute for Cosmic-Ray Research, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582, JapanL. BaldiniUniversità di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa, ItalyG. BarbielliniDipartimento di Fisica, Università di Trieste, I-34127 Trieste, ItalyD. BastieriDipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, I-35131 Padova, ItalyJ. Becerra GonzálezDepartment of Physics and Department of Astronomy, University of Maryland, College Park, MD 20742, USAR. BellazziniIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyC. MeeganIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyR. D. BlandfordW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAE. D. BloomW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAR. BoninoDipartimento di Fisica Generale “Amadeo Avogadro”, Università degli Studi di Torino, I-10125 Torino, ItalyE. BottaciniW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAP. BruelLaboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau, FranceR. BuehlerDeutsches Elektronen Synchrotron DESY, D-15738 Zeuthen, GermanyG. A. CaliandroConsorzio Interuniversitario per la Fisica Spaziale (CIFS), I-10133 Torino, ItalyR. A. CameronW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAM. CaragiuloDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyP. A. CaraveoINAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano, ItalyE. CavazzutiAgenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma, ItalyC. CecchiDipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia, ItalyC. C. CheungSpace Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USAJ. ChiangW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAG. ChiaroDipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, I-35131 Padova, ItalyS. CipriniAgenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma, ItalyJ. Cohen-TanugiLaboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier, FranceF. CostanzaIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyS. CutiniAgenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma, ItalyF. D’AmmandoUniversity of BolognaF. de PalmaIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyR. DesianteIstituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino, ItalyS. W. DigelW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USANiccolò Di LallaIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyMattia Di MauroW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAL. Di VenereDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyP. S. DrellW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAC. FavuzziDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyS. FeganLaboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau, FranceE. C. FerraraNASA Goddard Space Flight Center, Greenbelt, MD 20771, USAY. FukazawaDepartment of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanS. FunkErlangen Centre for Astroparticle Physics, D-91058 Erlangen, GermanyP. FuscoDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyF. GarganoIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyD. GasparriniAgenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma, ItalyN. GigliettoDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyF. GiordanoDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyM. GirolettiINAF Istituto di Radioastronomia, I-40129 Bologna, ItalyI. A. GrenierLaboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette, FranceL. GuillemotLaboratoire de Physique et Chimie de l’Environnement et de l’Espace—Université d’Orléans / CNRS, F-45071 Orléans Cedex 02, FranceS. GuiriecNASA Goddard Space Flight Center, Greenbelt, MD 20771, USAM. HayashidaInstitute for Cosmic-Ray Research, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582, JapanE. HaysNASA Goddard Space Flight Center, Greenbelt, MD 20771, USAD. HoranLaboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau, FranceG. JóhannessonScience Institute, University of Iceland, IS-107 Reykjavik, IcelandS. KenseiDepartment of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanD. KocevskiNASA Goddard Space Flight Center, Greenbelt, MD 20771, USAM. KussIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyG. La MuraDipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, I-35131 Padova, ItalyS. LarssonDepartment of Physics, KTH Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm, SwedenL. LatronicoIstituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino, ItalyJian LiInstitute of Space Sciences (IEEC-CSIC), Campus UAB, E-08193 Barcelona, SpainF. LongoDipartimento di Fisica, Università di Trieste, I-34127 Trieste, ItalyF. LoparcoDipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari, I-70126 Bari, ItalyB. LottCentre d’Études Nucléaires de Bordeaux Gradignan, IN2P3/CNRS, Université Bordeaux 1, BP120, F-33175 Gradignan Cedex, FranceM. N. LovelletteSpace Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USAP. LubranoIstituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia, ItalyG. MadejskiW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAJ. D. MagillDepartment of Physics and Department of Astronomy, University of Maryland, College Park, MD 20742, USAS. MalderaIstituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino, ItalyAlberto ManfredaIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyM. MayerDeutsches Elektronen Synchrotron DESY, D-15738 Zeuthen, GermanyM. N. MazziottaIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyP. F. MichelsonW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAN. MirabalNASA Goddard Space Flight Center, Greenbelt, MD 20771, USATsunefumi MizunoHiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanM. E. MonzaniW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAA. MorselliIstituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata,” I-00133 Roma, ItalyI. V. MoskalenkoW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAKrzysztof NalewajkoNicolaus Copernicus Astronomical Center, 00-716 Warsaw, PolandMichela NegroDipartimento di Fisica Generale “Amadeo Avogadro”, Università degli Studi di Torino, I-10125 Torino, ItalyE. NussLaboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier, FranceT. OhsugiHiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanE. OrlandoW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAD. PanequeMax-Planck-Institut für Physik, D-80805 München, GermanyJ. S. PerkinsNASA Goddard Space Flight Center, Greenbelt, MD 20771, USAM. Pesce-RollinsIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyF. PironLaboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier, FranceG. PivatoIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyT. A. PorterW. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USAG. PrincipeErlangen Centre for Astroparticle Physics, D-91058 Erlangen, GermanyR. RandoDipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, I-35131 Padova, ItalyM. RazzanoIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyS. RazzaqueDepartment of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South AfricaA. ReimerInstitut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck, AustriaJ. D. ScargleSpace Sciences Division, NASA Ames Research Center, Moffett Field, CA 94035-1000, USAC. SgróIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, ItalyM. SikoraNicolaus Copernicus Astronomical Center, 00-716 Warsaw, PolandD. SimoneIstituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, ItalyE. J. SiskindNYCB Real-Time Computing Inc., Lattingtown, NY 11560-1025, USAF. SpadaIstituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy
2016en
ABI
Аннотация
ABSTRACT On 2015 June 16, Fermi -LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak >100 MeV flux of ∼3.6 × 10 −5 photons cm −2 s −1 , averaged over orbital period intervals. It is historically the highest γ -ray flux observed from the source, including past EGRET observations, with the γ -ray isotropic luminosity reaching ∼10 49 erg s −1 . During the outburst, the Fermi spacecraft, which has an orbital period of 95.4 minutes, was operated in a special pointing mode to optimize the exposure for 3C 279. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi -LAT. The source flux variability was resolved down to 2-minute binned timescales, with flux doubling times of less than 5 minutes. The observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models. A minimum bulk jet Lorentz factor (Γ) of 35 is necessary to avoid both internal γ -ray absorption and super-Eddington jet power. In the standard external radiation Comptonization scenario, Γ should be at least 50 to avoid overproducing the synchrotron self-Compton component. However, this predicts extremely low magnetization (∼5 × 10 −4 ). Equipartition requires Γ as high as 120, unless the emitting region is a small fraction of the dissipation region. Alternatively, we consider γ rays originating as synchrotron radiation of γ e ∼ 1.6 × 10 6 electrons, in a magnetic field B ∼ 1.3 kG, accelerated by strong electric fields E ∼ B in the process of magnetoluminescence. At such short distance scales, one cannot immediately exclude the production of γ -rays in hadronic processes.
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