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27 results on '"Y. Khassen"'

1. Discovery of very high energy gamma rays from 1es 1440+122

Author

A. N. Otte, Geza Gyuk, E. Roache, M. P. Connolly, J. V. Tucci, Gernot Maier, S. P. Wakely, Abraham D. Falcone, Karlen Shahinyan, Wystan Benbow, N. Håkansson, Anna Barnacka, P. T. Reynolds, R. A. Ong, John L. Quinn, Ralph Bird, S. T. Griffiths, K. Sweeney, I. Telezhinsky, Jamie Holder, S. Federici, Martin Pohl, N. H. Park, J. Millis, J. Dumm, B. Zitzer, G. H. Sembroski, J. Grube, P. Kar, S. Godambe, Manel Errando, M. Kertzman, R. Welsing, M. J. Lang, L. C. Reyes, S. Kumar, K. Berger, Hugh Dickinson, D. S. Hanna, Xuhui Chen, Matteo Cerruti, Amy Furniss, Wei Cui, Henric Krawczynski, Y. Khassen, A. McCann, Q. Feng, A. O'Faolain de Bhroithe, David A. Williams, P. Kaaret, Lucy Fortson, D. Staszak, A. Popkow, Vladimir Vassiliev, H. Prokoph, Matthias Beilicke, J. S. Perkins, E. Pueschel, Markus Böttcher, J. Tyler, A. Wilhelm, A. Varlotta, A. Archer, J. V. Cardenzana, C. A. Johnson, E. Collins-Hughes, G. Hughes, David Kieda, Jodi Christiansen, J. D. Eisch, J. P. Finley, G. H. Gillanders, T. J. N. Nelson, S. McArthur, S. Griffin, K. Meagher, Jean-Francois Rajotte, S. Archambault, L. Ciupik, K. Ragan, V. Bugaev, H. Fleischhack, J. H. Buckley, A. W. Smith, A. S Madhavan, Gordon T. Richards, B. Behera, Daniel Nieto, and P. Moriarty

Subjects
extragalactic background light, multiwavelength observations, Astrophysics::High Energy Astrophysical Phenomena, bl-lacertae objects, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, bright blazars, 01 natural sciences, 7. Clean energy, law.invention, Telescope, law, 0103 physical sciences, intergalactic magnetic-field, Blazar, 010303 astronomy & astrophysics, Cherenkov radiation, Astrophysics::Galaxy Astrophysics, bl lacertae objects: general, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, tev blazars, Gamma ray, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, source catalog, gamma-rays: general, Redshift, large-area telescope, einstein slew survey, Crab Nebula, 13. Climate action, Space and Planetary Science, active galactic nuclei, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object, Fermi Gamma-ray Space Telescope
Abstract

The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the discovery of $\gamma$-ray emission from the blazar, which has a redshift $z$=0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standard deviations above the background with an integral flux of (2.8$\pm0.7_{\mathrm{stat}}\pm0.8_{\mathrm{sys}}$) $\times$ 10$^{-12}$ cm$^{-2}$ s$^{-1}$ (1.2\% of the Crab Nebula's flux) above 200 GeV. The measured spectrum is described well by a power law from 0.2 TeV to 1.3 TeV with a photon index of 3.1 $\pm$ 0.4$_{\mathrm{stat}}$ $\pm$ 0.2$_{\mathrm{sys}}$. Quasi-simultaneous multi-wavelength data from the Fermi Large Area Telescope (0.3--300 GeV) and the Swift X-ray Telescope (0.2--10 keV) are additionally used to model the properties of the emission region. A synchrotron self-Compton model produces a good representation of the multi-wavelength data. Adding an external-Compton or a hadronic component also adequately describes the data., Comment: 8 pages, 4 figures. Accepted for publication in MNRAS

Published
2016
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2. Gamma rays from the quasar PKS 1441+25: story of an escape

Author

Wystan Benbow, S. McArthur, O. M. Weiner, N. Håkansson, Henrike Fleischhack, M. J. Lang, P. Fortin, Ralph Bird, N. Kelley-Hoskins, L. Ciupik, R. Reeves, Geza Gyuk, Paul S. Smith, G. M. Madejski, Martin Pohl, Thomas W.-S. Holoien, A. O'Faolain de Bhroithe, J. Grube, Matthew J. Graham, R. A. Ong, A. McCann, K. Ragan, A. Petrashyk, K. Meagher, E. Pueschel, Marcos Santander, A. Wilhelm, Maria Krause, P. Kar, Benjamin J. Shappee, Talvikki Hovatta, S. G. Djorgovski, Paolo De Coppi, J. Tyler, M. P. Connolly, A. A. Mahabal, G. Ratliff, A. Archer, Xuhui Chen, J. H. Buckley, Lucy Fortson, Jodi Christiansen, S. Archambault, Q. Feng, P. Moriarty, Anthony C. S. Readhead, V. V. Vassiliev, A. Flinders, J. S. Perkins, Reshmi Mukherjee, Abraham D. Falcone, Hugh Dickinson, G. H. Gillanders, Karlen Shahinyan, David Kieda, Y. Khassen, T. B. Humensky, J. V. Tucci, Matteo Cerruti, N. W. Todd, Amy Furniss, G. H. Sembroski, D. S. Hanna, F. Krennrich, Daniel Nieto, A. Popkow, T. J. Pearson, Gernot Maier, J. L. Richards, Christopher S. Kochanek, T. Aune, Moritz Hütten, Wei Cui, John L. Quinn, B. Zitzer, P. Kaaret, J. V. Cardenzana, P. T. Reynolds, Walter Max-Moerbeck, Julien Rousselle, Manel Errando, S. Kumar, S. P. Wakely, C. A. Johnson, J. L. Prieto, Sinéad M. Griffin, Jonathan Biteau, Andrew J. Drake, J. P. Finley, J. P. Dumm, S. Vincent, A. W. Smith, J. D. Eisch, A. Weinstein, Gordon T. Richards, E. Roache, V. Bugaev, K. Z. Stanek, Nahee Park, Anushka Udara Abeysekara, Anna Barnacka, A. N. Otte, I. Telezhinsky, Jamie Holder, David A. Williams, D. Staszak, and ~

Subjects
extragalactic background light, Active galactic nucleus, Cosmology and Nongalactic Astrophysics (astro-ph.CO), spectra, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, telescope, Astrophysical jet, gamma rays: galaxies, emission, complete sample, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, variability, Gamma ray, Astronomy and Astrophysics, Quasar, radiation mechanisms: non-thermal, Galaxy, diffuse radiation, radiation, Extragalactic background light, mission, Space and Planetary Science, cosmology: observations, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, Schwarzschild radius, absorption, fermi blazars, quasars: individual (pks 1441+25-ver j1443+250), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The astrophysical journal / 2 815(2), L22 -(2015). doi:10.1088/2041-8205/815/2/L22, Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the universe. The detection of significant emission above 100 GeV from a distant quasar would show that some of the radiated gamma-rays escape pair-production interactions with low-energy photons, be it the extragalactic background light (EBL), or the radiation near the supermassive black hole lying at the jet's base. VERITAS detected gamma-ray emission up to ~200 GeV from PKS 1441+25 (z = 0.939) during 2015 April, a period of high activity across all wavelengths. This observation of PKS 1441+25 suggests that the emission region is located thousands of Schwarzschild radii away from the black hole. The gamma-ray detection also sets a stringent upper limit on the near-ultraviolet to near-infrared EBL intensity, suggesting that galaxy surveys have resolved most, if not all, of the sources of the EBL at these wavelengths., Published by Institute of Physics Publ., London

Published
2015
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3. Erratum: VERITAS deep observations of the dwarf spheroidal galaxy Segue 1 [Phys. Rev. D85, 062001 (2012)]

Author

M. P. Connolly, D. Staszak, K. Ragan, R. Dickherber, S. Thibadeau, L. Ciupik, A. Varlotta, H. J. Rose, D. S. Hanna, T. C. Arlen, P. Kaaret, D. B. Saxon, E. Collins-Hughes, G. H. Sembroski, G. Hughes, Matthias Beilicke, A. McCann, A. Cesarini, M. Vivier, John L. Quinn, Francesc Ferrer, S. Archambault, Reshmi Mukherjee, K. Tsurusaki, Gernot Maier, Nahee Park, S. P. Wakely, C. Skole, A. Bouvier, Geza Gyuk, J. E. Ward, R. A. Ong, Thomas Weisgarber, Daniel Gall, E. Aliu, Matthew R. Orr, David Kieda, K. L. Byrum, Jodi Christiansen, J. S. Perkins, S. M. Bradbury, G. Tešić, David A. Williams, Lucy Fortson, A. Cannon, Pratik Majumdar, V. V. Vassiliev, T. Aune, I. Telezhinsky, Jamie Holder, S. Godambe, J. P. Dumm, J. Ruppel, Q. Feng, L. C. Reyes, Henric Krawczynski, Amy Furniss, A. J.R. Weinstein, T. B. Humensky, M. Schroedter, Wei Cui, S. McArthur, V. Bugaev, Wystan Benbow, F. Krennrich, G. Finnegan, A. W. Smith, M. Theiling, A. S Madhavan, A. D. Falcone, E. Roache, G. D. Şentürk, H. Huan, J. H. Buckley, P. Moriarty, Nicola Galante, J. Grube, R. G. Wagner, N. Karlsson, Sinéad M. Griffin, Y. Khassen, G. Decerprit, S. Vincent, M. Kertzman, A. N. Otte, P. T. Reynolds, B. Zitzer, Manel Errando, J. P. Finley, T. C. Weekes, M. Pohl, K. Lee, and H. Prokoph

Subjects
Physics, Gravitation, Nuclear and High Energy Physics, Dark matter, Gamma ray, Astronomy, Astrophysics, Segue, Cosmology, Dwarf galaxy, Dwarf spheroidal galaxy
Published
2015
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4. The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

Author

MAGIC Collaboration, J. Aleksić(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. Ansoldi(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), L. A. Antonelli(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Antoranz(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), A. Babic(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), P. Bangale(Max-Planck-Institut für Physik, D-80805 München, Germany), U. Barres de Almeida(Max-Planck-Institut für Physik, D-80805 München, Germany), J. A. Barrio(Universidad Complutense, E-28040 Madrid, Spain), J. Becerra González(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), W. Bednarek(University of Lodz, PL-90236 Lodz, Poland), K. Berger(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), E. Bernardini(Deutsches Elektronen-Synchrotron), A. Biland(ETH Zurich, CH-8093 Zurich, Switzerland), O. Blanch(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), R. K. Bock(Max-Planck-Institut für Physik, D-80805 München, Germany), S. Bonnefoy(Universidad Complutense, E-28040 Madrid, Spain), G. Bonnoli(INAF National Institute for Astrophysics, I-00136 Rome, Italy), F. Borracci(Max-Planck-Institut für Physik, D-80805 München, Germany), T. Bretz(Universität Würzburg, D-97074 Würzburg, Germany), E. Carmona(Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain), A. Carosi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), D. Carreto Fidalgo(Universität Würzburg, D-97074 Würzburg, Germany), P. Colin(Max-Planck-Institut für Physik, D-80805 München, Germany), E. Colombo(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), J. L. Contreras(Universidad Complutense, E-28040 Madrid, Spain), J. Cortina(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. Covino(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Da Vela(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), F. Dazzi(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), A. De Angelis(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), G. De Caneva(Deutsches Elektronen-Synchrotron), B. De Lotto(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), C. Delgado Mendez(Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain), M. Doert(Technische Universität Dortmund, D-44221 Dortmund, Germany), A. Domínguez(Inst. de Astrofísica de Andalucía), D. Dominis Prester(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Dorner(Universität Würzburg, D-97074 Würzburg, Germany), M. Doro(Università di Padova and INFN, I-35131 Padova, Italy), S. Einecke(Technische Universität Dortmund, D-44221 Dortmund, Germany), D. Eisenacher(Universität Würzburg, D-97074 Würzburg, Germany), D. Elsaesser(Universität Würzburg, D-97074 Würzburg, Germany), E. Farina(Università dell'Insubria, Como, I-22100 Como, Italy), D. Ferenc(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), M. V. Fonseca(Universidad Complutense, E-28040 Madrid, Spain), L. Font(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), K. Frantzen(Technische Universität Dortmund, D-44221 Dortmund, Germany), C. Fruck(Max-Planck-Institut für Physik, D-80805 München, Germany), R. J. García López(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), M. Garczarczyk(Deutsches Elektronen-Synchrotron), D. Garrido Terrats(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), M. Gaug(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), G. Giavitto(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), N. Godinović(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), A. González Mu\ noz(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. R. Gozzini(Deutsches Elektronen-Synchrotron), A. Hadamek(Technische Universität Dortmund, D-44221 Dortmund, Germany), D. Hadasch(Institut de Ciències de l'Espai), A. Herrero(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), D. Hildebrand(ETH Zurich, CH-8093 Zurich, Switzerland), J. Hose(Max-Planck-Institut für Physik, D-80805 München, Germany), D. Hrupec(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), W. Idec(University of Lodz, PL-90236 Lodz, Poland), V. Kadenius(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), H. Kellermann(Max-Planck-Institut für Physik, D-80805 München, Germany), M. L. Knoetig(ETH Zurich, CH-8093 Zurich, Switzerland), J. Krause(Max-Planck-Institut für Physik, D-80805 München, Germany), J. Kushida(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. La Barbera(INAF National Institute for Astrophysics, I-00136 Rome, Italy), D. Lelas(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), N. Lewandowska(Universität Würzburg, D-97074 Würzburg, Germany), E. Lindfors(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), F. Longo(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), S. Lombardi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), M. López(Universidad Complutense, E-28040 Madrid, Spain), R. López-Coto(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), A. López-Oramas(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), E. Lorenz(Max-Planck-Institut für Physik, D-80805 München, Germany), I. Lozano(Universidad Complutense, E-28040 Madrid, Spain), M. Makariev(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), K. Mallot(Deutsches Elektronen-Synchrotron), G. Maneva(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), N. Mankuzhiyil(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), K. Mannheim(Universität Würzburg, D-97074 Würzburg, Germany), L. Maraschi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), B. Marcote(Universitat de Barcelona), M. Mariotti(Università di Padova and INFN, I-35131 Padova, Italy), M. Martínez(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), D. Mazin(Max-Planck-Institut für Physik, D-80805 München, Germany), U. Menzel(Max-Planck-Institut für Physik, D-80805 München, Germany), M. Meucci(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), J. M. Miranda(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), R. Mirzoyan(Max-Planck-Institut für Physik, D-80805 München, Germany), A. Moralejo(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), P. Munar-Adrover(Universitat de Barcelona), D. Nakajima(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. Niedzwiecki(University of Lodz, PL-90236 Lodz, Poland), K. Nilsson(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), N. Nowak(6,32,*), R. Orito(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. Overkemping(Technische Universität Dortmund, D-44221 Dortmund, Germany), S. Paiano(Università di Padova and INFN, I-35131 Padova, Italy), M. Palatiello(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), D. Paneque(6,*), R. Paoletti(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), J. M. Paredes(Universitat de Barcelona), X. Paredes-Fortuny(Universitat de Barcelona), S. Partini(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), M. Persic(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), F. Prada(Inst. de Astrofísica de Andalucía), P. G. Prada Moroni(Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy), E. Prandini(Università di Padova and INFN, I-35131 Padova, Italy), S. Preziuso(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), I. Puljak(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), R. Reinthal(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), W. Rhode(Technische Universität Dortmund, D-44221 Dortmund, Germany), M. Ribó(Universitat de Barcelona), J. Rico(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), J. Rodriguez Garcia(Max-Planck-Institut für Physik, D-80805 München, Germany), S. Rügamer(Universität Würzburg, D-97074 Würzburg, Germany), A. Saggion(Università di Padova and INFN, I-35131 Padova, Italy), K. Saito(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), M. Salvati(INAF National Institute for Astrophysics, I-00136 Rome, Italy), K. Satalecka(Universidad Complutense, E-28040 Madrid, Spain), V. Scalzotto(Università di Padova and INFN, I-35131 Padova, Italy), V. Scapin(Universidad Complutense, E-28040 Madrid, Spain), C. Schultz(Università di Padova and INFN, I-35131 Padova, Italy), T. Schweizer(Max-Planck-Institut für Physik, D-80805 München, Germany), S. N. Shore(Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy), A. Sillanpää(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), J. Sitarek(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), I. Snidaric(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Sobczynska(University of Lodz, PL-90236 Lodz, Poland), F. Spanier(Universität Würzburg, D-97074 Würzburg, Germany), V. Stamatescu(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), A. Stamerra(INAF National Institute for Astrophysics, I-00136 Rome, Italy), T. Steinbring(Universität Würzburg, D-97074 Würzburg, Germany), J. Storz(Universität Würzburg, D-97074 Würzburg, Germany), S. Sun(Max-Planck-Institut für Physik, D-80805 München, Germany), T. Surić(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), L. Takalo(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), F. Tavecchio(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Temnikov(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), T. Terzić(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Tescaro(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), M. Teshima(Max-Planck-Institut für Physik, D-80805 München, Germany), J. Thaele(Technische Universität Dortmund, D-44221 Dortmund, Germany), O. Tibolla(Universität Würzburg, D-97074 Würzburg, Germany), D. F. Torres(Institut de Ciències de l'Espai), T. Toyama(Max-Planck-Institut für Physik, D-80805 München, Germany), A. Treves(Università dell'Insubria, Como, I-22100 Como, Italy), M. Uellenbeck(Technische Universität Dortmund, D-44221 Dortmund, Germany), P. Vogler(ETH Zurich, CH-8093 Zurich, Switzerland), R. M. Wagner(Max-Planck-Institut für Physik, D-80805 München, Germany), F. Zandanel(Inst. de Astrofísica de Andalucía), R. Zanin(Universitat de Barcelona), VERITAS collaboration(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), (Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), S. Archambault(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), B. Behera(Deutsches Elektronen-Synchrotron), M. Beilicke(Department of Physics, Washington University, St. Louis, MO 63130, USA), W. Benbow(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), R. Bird(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), J. H. Buckley(Department of Physics, Washington University, St. Louis, MO 63130, USA), V. Bugaev(Department of Physics, Washington University, St. Louis, MO 63130, USA), M. Cerruti(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), X. Chen(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), L. Ciupik(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), E. Collins-Hughes(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), W. Cui(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. Dumm(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), J. D. Eisch(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), A. Falcone(Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802, USA), S. Federici(DESY, Platanenallee 6, 15738 Zeuthen, Germany), Q. Feng(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. P. Finley(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), H. Fleischhack(Deutsches Elektronen-Synchrotron), P. Fortin(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA), L. Fortson(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), A. Furniss(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), S. Griffin(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), S. T. Griffiths(Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA), J. Grube(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), G. Gyuk(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), D. Hanna(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), J. Holder(Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716, USA), G. Hughes(Deutsches Elektronen-Synchrotron), T. B. Humensky(Physics Department, Columbia University, New York, NY 10027, USA), C. A. Johnson(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), P. Kaaret(Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA), M. Kertzman(Department of Physics and Astronomy, DePauw University, Greencastle, IN 46135-0037, USA), Y. Khassen(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), D. Kieda(Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA), H. Krawczynski(Department of Physics, Washington University, St. Louis, MO 63130, USA), F. Krennrich(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), S. Kumar(Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716, USA), M. J. Lang(School of Physics, National University of Ireland Galway, University Road, Galway, Ireland), G. Maier(Deutsches Elektronen-Synchrotron), S. McArthur(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), K. Meagher(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), P. Moriarty(Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway, Ireland), R. Mukherjee(Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027, USA), R. A. Ong(Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA), A. N. Otte(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), N. Park(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), A. Pichel(Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67 - Sucursal 28), M. Pohl(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), A. Popkow(Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA), H. Prokoph(Deutsches Elektronen-Synchrotron), J. Quinn(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), K. Ragan(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), J. Rajotte(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), P. T. Reynolds(Department of Applied Physics and Instrumentation, Cork Institute of Technology, Bishopstown, Cork, Ireland), G. T. Richards(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), E. Roache(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), A. C. Rovero(Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67 - Sucursal 28), G. H. Sembroski(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), K. Shahinyan(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), D. Staszak(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), I. Telezhinsky(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), M. Theiling(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. V. Tucci(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. Tyler(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), A. Varlotta(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), S. P. Wakely(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), T. C. Weekes(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), A. Weinstein(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), R. Welsing(Deutsches Elektronen-Synchrotron), A. Wilhelm(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), D. A. Williams(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), B. Zitzer(Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA), External collaborators(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), (INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), M. Villata(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), C. Raiteri(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), H. D. Aller(Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042, USA), M. F. Aller(Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042, USA), W. P. Chen(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), B. Jordan(School of Cosmic Physics, Dublin Institute for Advanced Studies, Dublin, 2, Ireland), E. Koptelova(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), O. M. Kurtanidze(Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia), A. Lähteenmäki(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), B. McBreen(University College Dublin, Belfield, Dublin 4, Ireland), V. M. Larionov(Isaac Newton Institute of Chile, St. Petersburg Branch, St. Petersburg, Russia), C. S. Lin(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), M. G. Nikolashvili(Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia), E. Angelakis(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), M. Capalbi(ASI-Science Data Center, Via del Politecnico, I-00133 Rome, Italy), A. Carrami\ nana(Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla 72840, Mexico), L. Carrasco(Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla 72840, Mexico), P. Cassaro(INAF Istituto di Radioastronomia, Sezione di Noto, Contrada Renna Bassa, 96017 Noto), A. Cesarini(Department of Physics, University of Trento, I38050, Povo, Trento, Italy), L. Fuhrmann(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), M. Giroletti(INAF Istituto di Radioastronomia, 40129 Bologna, Italy), T. Hovatta(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), T. P. Krichbaum(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), H. A. Krimm(Astro Space Center of the Lebedev Physical Institute, 117997 Moscow, Russia), W. Max-Moerbeck(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), J. W. Moody(Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA), G. Maccaferri(INAF Istituto di Radioastronomia, Stazione Radioastronomica di Medicina, I-40059 Medicina), Y. Mori(Department of Physics, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551, Japan), I. Nestoras(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), A. Orlati(INAF Istituto di Radioastronomia, Stazione Radioastronomica di Medicina, I-40059 Medicina), C. Pace(Indiana University, Department of Astronomy, Swain Hall West 319, Bloomington, IN 47405-7105, USA), R. Pearson(Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA), M. Perri(INAF National Institute for Astrophysics, I-00136 Rome, Italy), A. C. S. Readhead(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), J. L. Richards(Department of Physics, Purdue University, 525 Northwestern Ave, West Lafayette, IN 47907), A. C. Sadun(Department of Physics, University of Colorado, Denver, CO 80220, USA), T. Sakamoto(Department of Physics and Mathematics, College of Science and 952 Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuoku, Sagamihara-shi Kanagawa 252-5258, Japan), J. Tammi(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), M. Tornikoski(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), Y. Yatsu(Department of Physics, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551, Japan), A. Zook(Department of Physics and Astronomy, Pomona College, Claremont CA 91711-6312, USA), Aleksić, J, Ansoldi, Stefano, Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., Barres De Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Carreto Fidalgo, D., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Delgado Mendez, C., Doert, M., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., García López, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giavitto, G., Godinović, N., González Muñoz, A., Gozzini, S. R., Hadamek, A., Hadasch, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Longo, Francesco, Lombardi, S., López, M., López Coto, R., López Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes Fortuny, X., Partini, S., Persic, M., Prada, F., Prada Moroni, P. G., Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rodriguezgarcia, J., Rügamer, S., Saggion, A., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Archambault, S., Behera, B., Beilicke, M., Benbow, W., Bird, R., Buckley, J. H., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Collins Hughes, E., Cui, W., Dumm, J., Eisch, J. D., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Fleischhack, H., Fortin, P., Fortson, L., Furniss, A., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Hanna, D., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Kumar, S., Lang, M. J., Maier, G., Mcarthur, S., Meagher, K., Moriarty, P., Mukherjee, R., Ong, R. A., Otte, A. N., Park, N., Pichel, A., Pohl, M., Popkow, A., Prokoph, H., Quinn, J., Ragan, K., Rajotte, J., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Sembroski, G. H., Shahinyan, K., Staszak, D., Telezhinsky, I., Theiling, M., Tucci, J. V., Tyler, J., Varlotta, A., Wakely, S. P., Weekes, T. C., Weinstein, A., Welsing, R., Wilhelm, A., Williams, D. A., Zitzer, B., Villata, M., Raiteri, C., Aller, H. D., Aller, M. F., Chen, W. P., Jordan, B., Koptelova, E., Kurtanidze, O. M., Lähteenmäki, A., Mcbreen, B., Larionov, V. M., Lin, C. S., Nikolashvili, M. G., Angelakis, E., Capalbi, M., Carramiñana, A., Carrasco, L., Cassaro, P., Cesarini, A., Fuhrmann, L., Giroletti, M., Hovatta, T., Krichbaum, T. P., Krimm, H. A., Max Moerbeck, W., Moody, J. W., Maccaferri, G., Mori, Y., Nestoras, I., Orlati, A., Pace, C., Pearson, R., Perri, M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Tammi, J., Tornikoski, M., Yatsu, Y., Zook, A., Department of Radio Science and Engineering, Aalto-yliopisto, Aalto University, and Universitat de Barcelona

Subjects
Astrofísica, Brightness, Ciencias Físicas, blazars, Astrophysics, telescope, x-ray variability, 01 natural sciences, Spectral line, BL Lacertae objects, individual, Mrk 421, purl.org/becyt/ford/1 [https], Raigs gamma, emission, MAGIC (telescope), 010303 astronomy & astrophysics, Physics, astro-ph.HE, High Energy Astrophysical Phenomena (astro-ph.HE), individual: Mrk 421 [BL Lacertae objects], Galaxies: BL Lacertae objects: individual: Markarian 421, Spectral energy distribution, Electrónica, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, power spectra, BL Lacertae object, tev photons, 0103 physical sciences, Nucli galàctic actiu, bl lacertae objects: individual: mrk 421, Blazar, Astronomy and Astrophysics, Space and Planetary Science, Active galactic nuclei, 010308 nuclear & particles physics, light curves, Gamma rays, Institut für Physik und Astronomie, purl.org/becyt/ford/1.3 [https], Light curve, Galaxies, Galàxies, Astronomía, Crab Nebula, optical variability, active galactic nuclei, Galàxies actives, Active galaxies, markarian-421, ddc:520
Abstract

We performed a 4.5-month multi-instrument campaign (from radio to VHE gamma rays) on Mrk421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical/UV and X-rays extending over the duration of the campaign. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multi-wavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk421 during non-flaring activity. Such a temporally extended X-ray/VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies., Comment: Accepted for publication in A&A, 18 pages, 14 figures (v2 has a small modification in the acknowledgments, and also corrects a typo in the field "author" in the metadata)

Published
2015
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5. The most powerful flaring activity from the NLSy1 PMN J0948+0022

Author

V. Bugaev, D. Staszak, J. P. Finley, Daniel Nieto, K. Ragan, T. B. Humensky, Josefin Larsson, Reshmi Mukherjee, K. Meagher, Talvikki Hovatta, G. H. Sembroski, L. Ciupik, P. Fortin, Abraham D. Falcone, J. V. Tucci, Gernot Maier, B. Zitzer, Ralph Bird, J. Tyler, Wystan Benbow, J. Grube, Manel Errando, S. Kumar, R. A. Ong, C. M. Raiteri, S. P. Wakely, S. T. Griffiths, Filippo D'Ammando, J. D. Eisch, K. Berger, Julien Rousselle, Hugh Dickinson, A. Weinstein, M. J. Lang, P. Kar, David A. Williams, John L. Quinn, N. Håkansson, Henrike Fleischhack, A. Varlotta, A. N. Otte, A. O'Faolain de Bhroithe, A. W. Smith, A. McCann, A. Popkow, Geza Gyuk, I. Telezhinsky, G. H. Gillanders, Gordon T. Richards, E. Roache, Jamie Holder, F. Krennrich, Marcos Santander, Matteo Cerruti, Walter Max-Moerbeck, Anthony C. S. Readhead, H. Prokoph, J. S. Perkins, David Kieda, J. V. Cardenzana, M. Pohl, Amy Furniss, L. Gérard, P. Moriarty, Matthias Beilicke, Lucy Fortson, M. Kertzman, J. L. Richards, Xuhui Chen, Y. Khassen, Vladimir Vassiliev, M. Orienti, E. Pueschel, P. T. Reynolds, Justin D. Finke, R. Welsing, Aalto-yliopisto, Aalto University, D'Ammando, F., Orienti, M., Finke, J., Raiteri, C. M., Hovatta, T., Larsson, J., Max-Moerbeck, W., Perkins, J., Readhead, A. C. S., Richards, J. L., Beilicke, M., Benbow, W., Berger, K., Bird, R., Bugaev, V., Cardenzana, J. V., Cerruti, M., Chen, X., Ciupik, L., Dickinson, H. J., Eisch, J. D., Errando, M., Falcone, A., Finley, J. P., Fleischhack, H., Fortin, P., Fortson, L., Furniss, A., Gerard, L., Gillanders, G. H., Griffiths, S. T., Grube, J., Gyuk, G., Håkansson, N., Holder, J., Humensky, T. B., Kar, P., Kertzman, M., Khassen, Y., Kieda, D., Krennrich, F., Kumar, S., Lang, M. J., Maier, G., Mccann, A., Meagher, K., Moriarty, P., Mukherjee, R., Nieto, D., de Bhróithe, A. O'Faoláin, Ong, R. A., Otte, A. N., Pohl, M., Popkow, A., Prokoph, H., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rousselle, J., Santander, M., Sembroski, G. H., Smith, A. W., Staszak, D., Telezhinsky, I., Tucci, J. V., Tyler, J., Varlotta, A., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Welsing, R., Williams, D. A., and Zitzer, B.

Subjects
extragalactic background light, multiwavelength observations, Active galactic nucleus, spectrum radio quasars, individual: PMN J0948+0022 [galaxies], Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, nuclei [galaxies], FOS: Physical sciences, galaxies: active, galaxies: individual: PMN J0948+0022, galaxies: nuclei, galaxies: Seyfert, gamma-rays: general, Owens Valley Radio Observatory, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, galaxies: active-galaxies: individual: pmn j0948+0022, line seyfert 1, Luminosity, law.invention, Telescope, law, Seyfert [galaxies], quasar pks 1510-089, relativistic jets, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, galactic nuclei, ta115, ta213, galaxies: individual: PMN J0948+0022, Astronomy, Astronomy and Astrophysics, gamma-rays: general, gamma-ray emission, galaxies: Seyfert, large-area telescope, x-ray, 13. Climate action, Space and Planetary Science, active [galaxies], ddc:520, Spectral energy distribution, galaxies: nuclei, Astrophysics - High Energy Astrophysical Phenomena, Radio astronomy, Flare, Fermi Gamma-ray Space Telescope, general [gamma-rays]
Abstract

Monthly notices of the Royal Astronomical Society 446(3), 2456 - 2467 (2015). doi:10.1093/mnras/stu2251, We report on multifrequency observations performed during 2012 December–2013 August of the first narrow-line Seyfert 1 galaxy detected in $\gamma$-rays, PMN J0948+0022 (z = 0.5846). A γ-ray flare was observed by the Large Area Telescope on board Fermi during 2012 December–2013 January, reaching a daily peak flux in the 0.1–100 GeV energy range of (155 $\pm$ 31) × $10^{−8}$ ph $cm^{−2} s^{−1}$ on 2013 January 1, corresponding to an apparent isotropic luminosity of $\sim$ 1.5 × $10^{48}$ erg $s^{−1}$. The $\gamma$-ray flaring period triggered Swift and Very Energetic Radiation Imaging Telescope Array System (VERITAS) observations in addition to radio and optical monitoring by Owens Valley Radio Observatory, Monitoring Of Jets in Active galactic nuclei with VLBA Experiments, and Catalina Real-time Transient Survey. A strong flare was observed in optical, UV, and X-rays on 2012 December 30, quasi-simultaneously to the $\gamma$-ray flare, reaching a record flux for this source from optical to $\gamma$-rays. VERITAS observations at very high energy (E > 100 GeV) during 2013 January 6–17 resulted in an upper limit of $F_{>0.2 TeV}$ < 4.0 × $10^{−12} ph cm^{−2} s^{−1}$. We compared the spectral energy distribution (SED) of the flaring state in 2013 January with that of an intermediate state observed in 2011. The two SEDs, modelled as synchrotron emission and an external Compton scattering of seed photons from a dust torus, can be modelled by changing both the electron distribution parameters and the magnetic field., Published by Oxford Univ. Press, Oxford

Published
2015
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6. VERITAS Observations of the BL Lac Object PG 1553+113

Author

D. Staszak, K. Ragan, S. McArthur, E. Aliu, A. Varlotta, J. Tyler, I. Telezhinsky, J. H. Buckley, B. Zitzer, Jamie Holder, L. C. Reyes, A. Archer, Matteo Cerruti, Hugh Dickinson, Amy Furniss, L. Ciupik, David A. Williams, D. S. Hanna, J. Grube, Manel Errando, A. N. Otte, Karen Byrum, Martin Pohl, A. O'Faolain de Bhroithe, J. D. Eisch, Geza Gyuk, M. P. Connolly, H. Prokoph, S. Kumar, A. Weinstein, J. Dumm, J. V. Tucci, J. P. Finley, P. Moriarty, G. Hughes, A. McCann, K. Meagher, G. H. Gillanders, Jean-Francois Rajotte, S. P. Wakely, Vladimir Vassiliev, Wystan Benbow, K. Berger, N. Galante, E. Pueschel, T. B. Humensky, David Kieda, Henric Krawczynski, A. S Madhavan, N. Håkansson, Gordon T. Richards, E. Roache, Sinéad M. Griffin, Anna Barnacka, Frank Krennrich, Xuhui Chen, B. Behera, P. Kaaret, J. V. Cardenzana, Daniel Nieto, A. Wilhelm, R. A. Ong, M. Kertzman, A. Popkow, C. A. Johnson, Lucy Fortson, S. T. Griffiths, N. H. Park, J. Millis, Q. Feng, S. Federici, Matthias Beilicke, V. Bugaev, Wei Cui, T. Aune, P. T. Reynolds, G. H. Sembroski, R. Welsing, Matthew R. Orr, J. S. Perkins, Y. Khassen, P. Kar, P. Fortin, Ralph Bird, M. J. Lang, John L. Quinn, Abraham D. Falcone, Karlen Shahinyan, and ~

Subjects
extragalactic background light, spectra, Astrophysics::High Energy Astrophysical Phenomena, blazars, pg-1553+113, FOS: Physical sciences, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, telescope, 10. No inequality, Blazar, optical spectroscopy, bl lacertae objects: general, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, model, Gamma rays, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma-rays, Redshift, radiation, Crab Nebula, Pair production, Extragalactic background light, Space and Planetary Science, ddc:520, lacertae objects, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object
Abstract

We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560\,GeV, is well described by a power law with a spectral index of $4.33 \pm 0.09$. The time-averaged integral flux above $200\,$GeV measured for this period was $(1.69 \pm 0.06) \times 10^{-11} \, \mathrm{ph} \, \mathrm{cm}^{-2} \, \mathrm{s}^{-1}$, corresponding to 6.9\% of the Crab Nebula flux. We also present the combined $\gamma$-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100~MeV to 560~GeV. The data are well fit by a power law with an exponential cutoff at $\rm {101.9 \pm 3.2 \, \mathrm{GeV}} $. The origin of the cutoff could be intrinsic to PG~1553+113 or be due to the $\gamma$-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of $\rm z \negthinspace > \negthinspace 0.395$ based on optical/UV observations of PG~1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of $z \negthinspace \leq \negthinspace 0.62$. A strongly-elevated mean flux of $(2.50 \pm 0.14) \times 10^{-11} \, \mathrm{ph} \, \mathrm{cm}^{-2} \, \mathrm{s}^{-1}$ (10.3\% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as $(4.44 \pm 0.71) \times 10^{-11} \, \mathrm{ph} \, \mathrm{cm}^{-2} \, \mathrm{s}^{-1}$ (18.3\% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a $\chi^2$ probability for a steady flux of 0.03\%., Comment: in press in ApJ, 2014

Published
2014
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7. Constraints on very high energy emission from grb 130427a

Author

P. Kaaret, S. McArthur, Wei Cui, J. Grube, Manel Errando, Q. Feng, H. Prokoph, R. Welsing, A. McCann, Geza Gyuk, J. V. Tucci, P. Fortin, Gernot Maier, Valerie Connaughton, L. Ciupik, O. M. Weiner, G. H. Sembroski, Péter Veres, K. Berger, S. Federici, A. Popkow, H. Fleischhack, J. H. Buckley, S. P. Wakely, Xuhui Chen, H. Krawczynski, I. Telezhinsky, Jamie Holder, M. J. Lang, A. Wilhelm, David Kieda, Anna Barnacka, A. S. Madhavan, K. Ragan, P. Moriarty, J. Tyler, A. Furniss, John L. Quinn, B. Zitzer, Wystan Benbow, G. H. Gillanders, E. Pueschel, Jonathan Biteau, A. Varlotta, N. Galante, Gareth Hughes, Frank Krennrich, Y. Khassen, T. B. Humensky, Julie McEnery, M. Kertzman, Jean-Francois Rajotte, A. W. Smith, Vladimir Vassiliev, A. O'Faolain de Bhroithe, Luis C. Reyes, J. V. Cardenzana, E. Roache, Gordon T. Richards, C. A. Johnson, N. Håkansson, David A. Williams, N. H. Park, Karen Byrum, M. Beilicke, Abraham D. Falcone, Karlen Shahinyan, J. D. Eisch, A. Weinstein, P. Kar, P. T. Reynolds, S. Vincent, Daniel Nieto, J. Millis, R. Mukherjee, Lucy Fortson, D. Staszak, Matteo Cerruti, Sylvia J. Zhu, Martin Pohl, K. Meagher, R. A. Ong, D. S. Hanna, V. Bugaev, S. T. Griffiths, J. S. Perkins, A. N. Otte, E. Aliu, T. Aune, S. Griffin, Hugh Dickinson, and J. P. Finley

Subjects
spectra, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, telescope, law.invention, Telescope, swift, Spitzer Space Telescope, law, component, tev, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, gamma-ray bursts, Gamma ray, GRB 130427A, Institut für Physik und Astronomie, Astronomy and Astrophysics, afterglows, Cherenkov Telescope Array, Redshift, gamma-ray burst: individual (grb 130427a), mission, 13. Climate action, Space and Planetary Science, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, limits, Fermi Gamma-ray Space Telescope
Abstract

Prompt emission from the very fluent and nearby (z=0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope for ~70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is also evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB 130427A ~71 ks (~20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redshift of the GRB, make VERITAS a very sensitive probe of the emission from GRB 130427A for E > 100 GeV. The non-detection and consequent upper limit derived place constraints on the synchrotron self-Compton model of high-energy gamma-ray emission from this burst., 22 pages, 4 figures, 1 table

Published
2014
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8. Very-high energy observations of the galactic center region by veritas in 2010-2012

Author

W. Chen, J. P. Finley, A. N. Otte, M. P. Connolly, Daniel Nieto, Abraham D. Falcone, Karlen Shahinyan, Matteo Cerruti, Amy Furniss, A. Wilhelm, L. Ciupik, B. Zitzer, M. J. Lang, J. Grube, S. Kumar, Xuhui Chen, Sinéad M. Griffin, J. Tyler, A. O'Faolain de Bhroithe, E. Pueschel, J. H. Buckley, N. H. Park, R. A. Ong, M. Kertzman, John L. Quinn, P. Kaaret, J. V. Cardenzana, P. Moriarty, J. V. Tucci, Gernot Maier, C. A. Johnson, J. Biteau, S. Federici, Reshmi Mukherjee, Karen Byrum, J. D. Eisch, S. P. Wakely, A. Popkow, Ralph Bird, Martin Pohl, A. Weinstein, S. T. Griffiths, S. McArthur, J. Dumm, G. H. Sembroski, Q. Feng, J. S. Perkins, Anna Barnacka, N. Galante, A. Archer, R. Welsing, A. McCann, Wei Cui, Anna Zajczyk, David A. Williams, A. W. Smith, V. Bugaev, Gordon T. Richards, David Kieda, E. Roache, P. Kar, D. Staszak, K. Ragan, K. Meagher, Jean-Francois Rajotte, Matthias Beilicke, Lucy Fortson, K. Berger, Henric Krawczynski, I. Telezhinsky, Jamie Holder, L. C. Reyes, P. T. Reynolds, S. Vincent, Y. Khassen, Hugh Dickinson, D. S. Hanna, A. Varlotta, Wystan Benbow, G. Hughes, N. Håkansson, Henrike Fleischhack, H. Prokoph, and Geza Gyuk

Subjects
Astrophysics::High Energy Astrophysical Phenomena, galaxy: center, Dark matter, black hole physics, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, molecular clouds, gamma-ray source, gamma rays: galaxies, emission, crab-nebula, Supernova remnant, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, Supermassive black hole, variability, Galactic Center, Institut für Physik und Astronomie, Astronomy, Astronomy and Astrophysics, source catalog, radiation mechanisms: non-thermal, Astrophysics - Astrophysics of Galaxies, methods: data analysis, Galaxy, dark-matter, Space and Planetary Science, astroparticle physics, Astrophysics of Galaxies (astro-ph.GA), ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, sgr-a-asterisk, magic telescope, discovery, Fermi Gamma-ray Space Telescope
Abstract

The Galactic center is an interesting region for high-energy (0.1-100 GeV) and very-high-energy (E > 100 GeV) gamma-ray observations. Potential sources of GeV/TeV gamma-ray emission have been suggested, e.g., the accretion of matter onto the supermassive black hole, cosmic rays from a nearby supernova remnant (e.g. SgrA East), particle acceleration in a plerion, or the annihilation of dark matter particles. The Galactic center has been detected by EGRET and by Fermi/LAT in the MeV/GeV energy band. At TeV energies, the Galactic center was detected with moderate significance by the CANGAROO and Whipple 10 m telescopes and with high significance by H.E.S.S., MAGIC, and VERITAS. We present the results from three years of VERITAS observations conducted at large zenith angles resulting in a detection of the Galactic center on the level of 18 standard deviations at energies above ~2.5TeV. The energy spectrum is derived and is found to be compatible with hadronic, leptonic and hybrid emission models discussed in the literature. Future, more detailed measurements of the high-energy cutoff and better constraints on the high-energy flux variability will help to refine and/or disentangle the individual models., 15 pages, 7 figures, accepted for publication in ApJ

Published
2014
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9. Spatially Resolving the very high Energy Emission from MGRO J2019+37 with VERITAS

Author

I. Telezhinsky, Jamie Holder, S. Vincent, A. Popkow, L. C. Reyes, A. Bouvier, Abraham D. Falcone, Eric V. Gotthelf, Karlen Shahinyan, Sinéad M. Griffin, P. Fortin, P. Kaaret, Jean-Francois Rajotte, Ralph Bird, T. Aune, B. Behera, Daniel Nieto, J. P. Finley, Martin Pohl, C. A. Johnson, M. Kertzman, D. Staszak, D. S. Hanna, T. B. Humensky, J. Dumm, Wystan Benbow, K. Ragan, A. O'Faolain de Bhroithe, L. Ciupik, F. Krennrich, John L. Quinn, V. Bugaev, E. Aliu, R. A. Ong, Matthias Beilicke, B. Zitzer, Oleg Kargaltsev, J. V. Tucci, S. T. Griffiths, Mallory S. E. Roberts, Gernot Maier, K. Berger, J. Grube, Manel Errando, A. McCann, Q. Feng, N. Galante, Y. Khassen, H. Prokoph, Amanda Weinstein, S. McArthur, Xuhui Chen, A. N. Otte, S. P. Wakely, M. P. Connolly, Dirk Pandel, A. W. Smith, S. Federici, A. S Madhavan, David Kieda, Henrike Fleischhack, Gordon T. Richards, E. Roache, G. H. Gillanders, Reshmi Mukherjee, G. Hughes, M. J. Lang, A. Wilhelm, Matteo Cerruti, Amy Furniss, David A. Williams, Wei Cui, P. T. Reynolds, Geza Gyuk, Vikram V. Dwarkadas, J. Tyler, Lucy Fortson, P. Moriarty, N. H. Park, J. Millis, J. H. Buckley, G. H. Sembroski, and R. Welsing

Subjects
stars, Photon, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, supernovae : individual (ctb 87), galactic plane, 01 natural sciences, Spectral line, Pulsar, pulsars : individual (psr j2021+3651), Observatory, 0103 physical sciences, pulsar wind nebula, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, cygnus region, hess, 010308 nuclear & particles physics, Star formation, Institut für Physik und Astronomie, Astronomy, Astronomy and Astrophysics, gamma-ray emission, gamma rays : stars, psr j2021+3651, milagro, Supernova, 13. Climate action, Space and Planetary Science, Milagro, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, discovery, associations
Abstract

We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended ($\sim2^{\circ}$) unidentified Milagro source is located towards the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the $0.65 - 10$ TeV energy range by a power-law model with photon index $2.3\pm0.4$. VER J2019+368 is a bright extended ($\sim1^{\circ}$) source, that likely accounts for the bulk of the Milagro emission and is notably coincident with PSR J2021+3651 and the star formation region Sh 2-104. Its spectrum in the range $1-30$ TeV is well fit with a power-law model of photon index $1.75\pm0.3$, among the hardest values measured in the VHE band, comparable to that observed near Vela-X. We explore the unusual spectrum and morphology in the radio and X-ray bands to constrain possible emission mechanisms for this source., 9 pages, 8 figures, accepted for publication in the Astrophysical Journal

Published
2014
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10. Investigating the TeV morpholoy of MGRO J1908+06 with veritas

Author

P. Kaaret, J. Grube, S. Archambault, M. P. Connolly, Manel Errando, J. V. Cardenzana, J. E. Ward, Wei Cui, K. Berger, John L. Quinn, M. Kertzman, J. V. Tucci, P. Fortin, A. Varlotta, Gernot Maier, E. Collins-Hughes, Frank Krennrich, A. O'Faolain de Bhroithe, S. Vincent, G. H. Sembroski, M. Beilicke, H. Prokoph, R. Mukherjee, N. Galante, S. P. Wakely, M. J. Lang, R. Welsing, D. Gall, G. Ratliff, A. Wilhelm, Q. Feng, Gareth Hughes, Martin Pohl, H. Fleischhack, R. A. Ong, Xuhui Chen, A. W. Smith, Y. Khassen, S. Federici, David Kieda, Dirk Pandel, J. Dumm, J. H. Buckley, Gordon T. Richards, T. B. Humensky, K. Meagher, S. T. Griffiths, Vikram V. Dwarkadas, K. Ragan, E. Roache, D. S. Hanna, B. Behera, Luis C. Reyes, A. Furniss, Daniel Nieto, D. Staszak, Abraham D. Falcone, Karlen Shahinyan, N. H. Park, P. T. Reynolds, Jean-Francois Rajotte, V. Bugaev, Lucy Fortson, J. P. Finley, Sunil Kumar, A. Popkow, F. Sheidaei, J. Millis, J. Tyler, A. Weinstein, P. Moriarty, S. Griffin, E. Aliu, Ralph Bird, I. Telezhinsky, Jamie Holder, A. S. Madhavan, Wystan Benbow, A. N. Otte, Geza Gyuk, Julien Rousselle, L. Ciupik, K. Tsurusaki, G. H. Gillanders, Vladimir Vassiliev, Matteo Cerruti, T. Aune, and A. McCann

Subjects
High energy, Photon, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, g40.5-0.5, Astrophysics, array, 01 natural sciences, Pulsar wind nebula, galactic plane, remnant, Pulsar, pulsars: individual (psr j1907+0602), Observatory, 0103 physical sciences, pulsar wind nebula, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, gamma-ray burst: individual (mgro j1908+06, ver j1907+062), 010308 nuclear & particles physics, Sigma, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma rays: general, gamma-ray emission, milagro, psr j1907+0602, 13. Climate action, Space and Planetary Science, ism: supernova remnants, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on deep observations of the extended TeV gamma-ray source MGRO J1908+06 made with the VERITAS very high energy (VHE) gamma-ray observatory. Previously, the TeV emission has been attributed to the pulsar wind nebula (PWN) of the Fermi-LAT pulsar PSR J1907+0602. We detect MGRO J1908+06 at a significance level of 14 standard deviations (14 sigma) and measure a photon index of 2.20 +/- 0.10_stat +/- 0.20_sys. The TeV emission is extended, covering the region near PSR J1907+0602 and also extending towards SNR G40.5--0.5. When fitted with a 2-dimensional Gaussian, the intrinsic extension has a standard deviation of sigma_src = 0.44 +/- 0.02 degrees. In contrast to other TeV PWNe of similar age in which the TeV spectrum softens with distance from the pulsar, the TeV spectrum measured near the pulsar location is consistent with that measured at a position near the rim of G40.5--0.5, 0.33 degrees away., To appear in ApJ, 8 pages

Published
2014
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11. Test of Models of the Cosmic Infrared Background with Multiwavelength Observations of the Blazar 1ES 1218+30.4 in 2009

Author

Wystan Benbow, Daniel Nieto, A. N. Otte, M. P. Connolly, A. Bouvier, L. Ciupik, R. Dickherber, Geza Gyuk, T. Aune, P. T. Reynolds, P. Moriarty, S. McArthur, Ralph Bird, S. Federici, J. P. Finley, J. H. Buckley, Sinéad M. Griffin, Matthias Beilicke, P. Majumdar, Lucy Fortson, N. Galante, M. J. Lang, R. A. Ong, A. Varlotta, M. Kertzman, A. S Madhavan, Markus Böttcher, A. Lamerato, Q. Feng, John L. Quinn, Gordon T. Richards, E. Roache, G. D. Şentürk, Gernot Maier, D. S. Hanna, T. C. Arlen, Wei Cui, C. Gusbar, P. Roustazadeh, G. Hughes, Vladimir Vassiliev, H. Prokoph, S. P. Wakely, R. Welsing, Matthew R. Orr, V. Bugaev, C. Skole, G. H. Gillanders, Daniel Gall, P. Kaaret, Y. Khassen, E. Collins-Hughes, A. Iii. Garson, G. Tešić, Amy Furniss, Henric Krawczynski, S. Vincent, D. B. Saxon, N. H. Park, J. Millis, K. Li, J. S. Perkins, Martin Pohl, J. Dumm, G. H. Sembroski, S. Archambault, Reshmi Mukherjee, A. Weinstein, A. D. Falcone, A. McCann, A. O'Faolain de Bhroithe, David Kieda, M. Theiling, I. Telezhinsky, Jamie Holder, David A. Williams, D. Staszak, K. Ragan, B. Zitzer, J. Grube, Manel Errando, and A. Popkow

Subjects
Smithsonian institution, Astrophysics::High Energy Astrophysical Phenomena, Cosmic background radiation, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, cosmic background radiation, timing explorer, Cosmic infrared background, gamma rays: galaxies, strong flares, Blazar, bl lacertae objects: general, Diffuse radiation, Physics, gamma-ray observations, bl lacertae objects: individual (1es1218+30.4), particle-acceleration, tev blazars, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, Visible radiation, galaxies: jets, veritas observations, diffuse radiation, Red shift, large-area telescope, x-ray, Space and Planetary Science, active galactic nuclei, extragalactic magnetic-fields, ddc:520
Abstract

We present the results of a multi-wavelength campaign targeting the blazar 1ES 1218+30.4 with observations with the 1.3 m McGraw-Hill optical telescope, the Rossi X-ray Timing Explorer (RXTE), the Fermi Gamma-Ray Space Telescope, and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The RXTE and VERITAS observations were spread over a 13 day period and revealed clear evidence for flux variability, and a strong X-ray and gamma-ray flare on 2009 February 26 (MJD 54888). The campaign delivered a well-sampled broadband energy spectrum with simultaneous RXTE and VERITAS very high energy (VHE, > 100 GeV) observations, as well as contemporaneous optical and Fermi observations. The 1ES 1218+30.4 broadband energy spectrum-the first with simultaneous X-ray and VHE gamma-ray energy spectra-is of particular interest as the source is located at a high cosmological redshift for a VHE source (z = 0.182), leading to strong absorption of VHE gamma rays by photons from the optical/infrared extragalactic background light (EBL) via gamma VHE +gamma EBL -> e(+) e(-)pair-creation processes. We model the data with a one-zone synchrotron self-Compton (SSC) emission model and with the extragalactic absorption predicted by several recent EBL models. We find that the observations are consistent with the SSC scenario and all the EBL models considered in this work. We discuss observational and theoretical avenues to improve on the EBL constraints.

Published
2014
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12. Observation of Markarian 421 in TeV gamma rays over a 14-year time span

Author

M. J. Lang, J. Tyler, J. H. Buckley, D. A. Carter-Lewis, E. Collins-Hughes, G. H. Gillanders, S. P. Wakely, Daniel Gall, L. Ciupik, N. Galante, E. Roache, A. N. Otte, H. Krawczynski, T. Reynolds, M. P. Connolly, D. S. Hanna, Ralph Bird, G. Finnegan, Geza Gyuk, K. Ragan, A. W. Smith, C. Duke, A. Pichel, G. H. Sembroski, Lucy Fortson, R. Welsing, Abraham D. Falcone, T. C. Arlen, V. Bugaev, Matthew R. Orr, J. P. Finley, Wei Cui, Y. Khassen, V. A. Acciari, T. Aune, T. C. Weekes, S. M. Bradbury, John Toner, A. C. Rovero, A. Cesarini, A. S. Madhavan, Wystan Benbow, Martin Pohl, John L. Quinn, P. Moriarty, R. A. Ong, K. G. Gibbs, J. Dumm, J. S. Perkins, S. J. Fegan, S. Federici, A. Weinstein, Stephanie Wissel, M. Schroedter, I. de la Calle Perez, A. Varlotta, A. Bouvier, P. Kaaret, J. E. Ward, David Kieda, M. Theiling, Sinéad M. Griffin, M. Kertzman, A. O'Faolain de Bhroithe, D. J. Fegan, T. J. N. Nelson, J. A. Gaidos, David A. Williams, I. Telezhinsky, T. B. Humensky, Julie McEnery, D. Horan, D. Petry, J. Grube, M. Vivier, and F. Krennrich

Subjects
multiwavelength observations, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, Astrophysics, telescope, timing explorer, 01 natural sciences, Spectral line, law.invention, purl.org/becyt/ford/1 [https], Telescope, law, blazar markarian-421, emission, 0103 physical sciences, crab-nebula, flare, AGN, Blazar, tev gamma rays, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Markarian 421, 010308 nuclear & particles physics, markarian 421, Gamma ray, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], TeV gamma rays, Astronomía, Crab Nebula, correlated variability, active galactic nuclei, ddc:540, agn, Astrophysics - High Energy Astrophysical Phenomena, Markarian galaxies, CIENCIAS NATURALES Y EXACTAS, energy, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4 hours of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The time-averaged flux from Markarian 421 over this period was 0.446$\pm$0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units., Comment: 29 pages, 15 figures. Accepted for publication in Astroparticle Physics

Published
2014
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13. A Three-Year Multi-Wavelength Study of the Very-High-Energy $\gamma$-Ray Blazar 1ES 0229+200

Author

F. Krennrich, A. McCann, A. Popkow, E. Aliu, M. Theiling, T. Aune, B. Zitzer, J. S. Perkins, J. H. Buckley, Wystan Benbow, V. V. Vassiliev, Manel Errando, A. O'Faolain de Bhroithe, A. Varlotta, K. Meagher, D. B. Kieda, P. Fortin, A. N. Otte, Anna Zajczyk, J. P. Dumm, Henrike Fleischhack, M. P. Connolly, John L. Quinn, Matthias Beilicke, S. Federici, Ralph Bird, P. Moriarty, Nicola Galante, J. Grube, I. Telezhinsky, Gernot Maier, J. P. Finley, B. Behera, Daniel Nieto, L. Ciupik, T. C. Weekes, Jamie Holder, Nahee Park, Xuhui Chen, K. L. Byrum, H. Prokoph, R. A. Ong, Y. Khassen, L. C. Reyes, S. McArthur, S. T. Griffiths, S. Archambault, Reshmi Mukherjee, J. Millis, S. P. Wakely, Wei Cui, V. Bugaev, D. Staszak, K. Ragan, A. W. Smith, D. S. Hanna, A. S Madhavan, C. Duke, Gordon T. Richards, T. C. Arlen, E. Roache, P. Kaaret, P. T. Reynolds, David A. Williams, R. Welsing, C. A. Johnson, Lucy Fortson, S. Vincent, Henric Krawczynski, A. J.R. Weinstein, M. J. Lang, Martin Pohl, G. H. Sembroski, A. D. Falcone, Q. Feng, T. B. Humensky, K. Berger, Matteo Cerruti, Amy Furniss, Sinéad M. Griffin, Gareth Hughes, M. Kertzman, A. Bouvier, Geza Gyuk, Pratik Majumdar, and G. H. Gillanders

Subjects
extragalactic background light, bl lacertae objects: individual (1es 0229+200, ver j0232+202), Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, magnetic fields, 01 natural sciences, bl lacertae objects, 0103 physical sciences, intergalactic magnetic-field, Blazar, 010303 astronomy & astrophysics, bl lacertae objects: general, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, space-telescope, distant blazars, tev blazars, 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma rays: general, diffuse radiation, large-area telescope, Crab Nebula, x-ray, Extragalactic background light, Space and Planetary Science, active galactic nuclei, Spectral energy distribution, Intergalactic travel, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, lorentz factor, Fermi Gamma-ray Space Telescope, BL Lac object
Abstract

The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma ~ 2.5), very-high-energy-emitting (E > 100 GeV) gamma-ray blazar. Very-high-energy measurements of this active galactic nucleus have been used to place constraints on the intensity of the extragalactic background light and the intergalactic magnetic field. A multi-wavelength study of this object centered around very-high-energy observations by VERITAS is presented. This study obtained, over a period of three years, an 11.7 standard deviation detection and an average integral flux F(E>300 GeV) = (23.3 +- 2.8_stat +- 5.8_sys) x 10^-9 photons m^-2 s^-1, or 1.7% of the Crab Nebula's flux (assuming the Crab Nebula spectrum measured by H.E.S.S). Supporting observations from Swift and RXTE are analyzed. The Swift observations are combined with previously published Fermi observations and the very-high-energy measurements to produce an overall spectral energy distribution which is then modeled assuming one-zone synchrotron-self-Compton emission. The chi^2 probability of the TeV flux being constant is 1.6%. This, when considered in combination with measured variability in the X-ray band, and the demonstrated variability of many TeV blazars, suggests that the use of blazars such as 1ES 0229+200 for intergalactic magnetic field studies may not be straightforward and challenges models that attribute hard TeV spectra to secondary gamma-ray production along the line of sight., Accepted for publication in ApJ

Published
2014
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14. Discovery of TeV Gamma-ray Emission Toward Supernova Remnant SNR G78.2+2.1

Author

M. Kertzman, A. O'Faolain de Bhroithe, M. Schroedter, Vikram V. Dwarkadas, S. Vincent, Wei Cui, M. J. Lang, S. Thibadeau, A. N. Otte, M. P. Connolly, A. McCann, R. Mukherjee, D. B. Saxon, N. H. Park, J. Millis, T. Aune, J. E. Ward, A. Cesarini, P. Moriarty, John L. Quinn, T. B. Humensky, A. Furniss, Frank Krennrich, A. S. Madhavan, G. Tešić, Gernot Maier, H. Prokoph, A. Varlotta, Wystan Benbow, S. P. Wakely, Eric V. Gotthelf, E. Roache, J. P. Finley, S. Archambault, H. J. Rose, R. A. Ong, Ralph Bird, G. H. Sembroski, P. Kaaret, Amanda Weinstein, Abraham D. Falcone, R. Welsing, Vladimir Vassiliev, L. Ciupik, T. C. Weekes, J. Grube, D. Gall, Geza Gyuk, K. Tsurusaki, S. Federici, Manel Errando, T. C. Arlen, J. H. Buckley, G. H. Gillanders, P. Majumdar, T. J. N. Nelson, S. McArthur, N. Galante, S. Godambe, Dirk Pandel, S. Griffin, G. Finnegan, C. Skole, C. Duke, David A. Williams, N. Karlsson, G. D. Şentürk, T. Weisgarber, H. Huan, E. Aliu, I. Telezhinsky, K. Lee, Jamie Holder, A. Popkow, J. Tyler, A. Bouvier, D. S. Hanna, V. Bugaev, J. S. Perkins, Martin Pohl, Q. Feng, J. Dumm, P. T. Reynolds, David Kieda, M. Theiling, Lucy Fortson, Karen Byrum, S. M. Bradbury, A. Cannon, E. Collins-Hughes, H. Krawczynski, M. Beilicke, M. Orr, G. Hughes, K. Ragan, B. Zitzer, J. Ruppel, R. Dickherber, Y. Khassen, and Luis C. Reyes

Subjects
catalog, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, cosmic rays, Observatory, 0103 physical sciences, origin, Supernova remnant, 010303 astronomy & astrophysics, 2cg078+2, Astrophysics::Galaxy Astrophysics, acceleration of particles, Physics, search, High Energy Astrophysical Phenomena (astro-ph.HE), particle-acceleration, 010308 nuclear & particles physics, hess, Gamma ray, Institut für Physik und Astronomie, counterpart, Astronomy and Astrophysics, gamma rays: general, Particle acceleration, Crab Nebula, Space and Planetary Science, ism: supernova remnants, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, fermi
Abstract

We report the discovery of an unidentified, extended source of very-high-energy (VHE) gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hours of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0.23^{\circ} \pm 0.03^{\circ} (stat)+0.04^{\circ}_{-0.02}^{\circ}(sys) and its spectrum is well-characterized by a differential power law (dN/dE = N_0 \times (E/TeV)^{-\Gamma}) with a photon index of {\Gamma} = 2.37 \pm 0.14 (stat) \pm 0.20 (sys) and a flux normalization of N0 = 1.5 \pm 0.2 (stat) \pm 0.4(sys) \times 10^-12 ph TeV^{-1} cm^{-2} s^{-1}. This yields an integral flux of 5.2 \pm 0.8 (stat) \pm 1.4 (sys) \times 10^-12 ph cm^{-2} s^{-1} above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the supernova remnant shock., Comment: 18 pages, 5 figures, accepted for publication in ApJ

Published
2013
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15. VERITAS Observations of the Microquasar Cygnus X-3

Author

A. Varlotta, Martin Pohl, J. S. Perkins, David Kieda, P. Moriarty, Nicola Galante, J. Grube, M. P. Connolly, David A. Williams, M. J. Lang, Xuhui Chen, Matthias Beilicke, Abraham D. Falcone, I. Telezhinsky, A. McCann, G. H. Sembroski, Daniel Nieto, Wei Cui, Q. Feng, A. O'Faolain de Bhroithe, G. H. Gillanders, Jamie Holder, Y. Khassen, H. Prokoph, Henric Krawczynski, A. J.R. Weinstein, D. S. Hanna, F. Sheidaei, K. Berger, Geza Gyuk, T. B. Humensky, L. C. Reyes, Karen Byrum, P. T. Reynolds, Pratik Majumdar, Sinéad M. Griffin, D. Staszak, K. Ragan, Matteo Cerruti, Gareth Hughes, M. Kertzman, B. Zitzer, Lucy Fortson, R. A. Ong, Amy Furniss, S. Vincent, A. W. Smith, A. S Madhavan, Ralph Bird, C. Duke, Gordon T. Richards, Manel Errando, E. Roache, S. Federici, S. T. Griffiths, Michael L. McCollough, A. Bouvier, P. Kaaret, Wystan Benbow, S. McArthur, S. Archambault, Reshmi Mukherjee, A. Popkow, A. N. Otte, V. Bugaev, John L. Quinn, N. H. Park, J. V. Tucci, Gernot Maier, J. P. Finley, S. P. Wakely, T. C. Weekes, D. Pandel, L. Ciupik, Jean-Francois Rajotte, J. Tyler, J. H. Buckley, J. P. Dumm, and M. Theiling

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Radiation imaging, FOS: Physical sciences, Astrophysics, gamma rays: stars, 01 natural sciences, law.invention, Telescope, x-rays: individual (cygnus x-3), law, 0103 physical sciences, cyg x-3, 010303 astronomy & astrophysics, acceleration of particles, Physics, search, High Energy Astrophysical Phenomena (astro-ph.HE), binaries: close, 010308 nuclear & particles physics, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma-ray emission, large-area telescope, scattering halo, x-ray, mission, Space and Planetary Science, cherenkov telescopes, ddc:520, relativistic jet, Astrophysics - High Energy Astrophysical Phenomena, constraints
Abstract

We report results from TeV gamma-ray observations of the microquasar Cygnus X-3. The observations were made with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) over a time period from 2007 June 11 to 2011 November 28. VERITAS is most sensitive to gamma rays at energies between 85 GeV to 30 TeV. The effective exposure time amounts to a total of about 44 hours, with the observations covering six distinct radio/X-ray states of the object. No significant TeV gamma-ray emission was detected in any of the states, nor with all observations combined. The lack of a positive signal, especially in the states where GeV gamma rays were detected, places constraints on TeV gamma-ray production in Cygnus X-3. We discuss the implications of the results., Comment: 23 pages, 4 figures, 3 tables, accepted for publication in ApJ

Published
2013
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16. MULTIWAVELENGTH OBSERVATIONS OF THE TeV BINARY LS I +61° 303 WITH VERITAS, Fermi -LAT, AND Swift /XRT DURING A TeV OUTBURST

Author

S. Archambault, Gernot Maier, A. McCann, R. A. Ong, P. T. Reynolds, Lucy Fortson, N. Galante, S. P. Wakely, J. P. Finley, P. Fortin, A. D. Falcone, S. T. Griffiths, Y. Khassen, T. C. Weekes, A. W. Smith, Martin Pohl, Gordon T. Richards, Geza Gyuk, M. J. Lang, J. Dumm, M. Beilicke, S. Griffin, A. N. Otte, P. Majumdar, M. P. Connolly, K. Berger, L. Ciupik, B. Behera, D. Staszak, N. H. Park, Wystan Benbow, D. S. Hanna, John L. Quinn, G. H. Gillanders, Matteo Cerruti, E. Aliu, C. Skole, V. Bugaev, A. Varlotta, S. Federici, Q. Feng, A. Furniss, J. S. Perkins, David Kieda, G. Ratliff, S. Vincent, P. Kaaret, Gareth Hughes, E. Roache, R. Mukherjee, I. Telezhinsky, P. Moriarty, Jamie Holder, Ralph Bird, M. Kertzman, Xuhui Chen, J. Grube, A. O'Faolain de Bhroithe, A. Weinstein, A. Bouvier, Frank Krennrich, S. McArthur, F. Sheidaei, Wei Cui, H. Prokoph, T. B. Humensky, A. Popkow, Anna Zajczyk, J. Tyler, K. Ragan, B. Zitzer, Jean-Francois Rajotte, G. H. Sembroski, and R. Welsing

Subjects
Swift, Astrophysics::High Energy Astrophysical Phenomena, Binary number, FOS: Physical sciences, Astrophysics, telescope, gamma rays: stars, 01 natural sciences, law.invention, spectrum, Telescope, star, law, gamma-ray binary, 0103 physical sciences, emission, +61-degrees-303, 010303 astronomy & astrophysics, computer.programming_language, acceleration of particles, relativistic processes, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astronomy and Astrophysics, binaries: general, x-ray, Space and Planetary Science, x-rays: binaries, Spectral energy distribution, ddc:520, Satellite, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, computer, Fermi Gamma-ray Space Telescope
Abstract

We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61 303 with the VERITAS telescope array (>200 GeV), Fermi-LAT (0.3-300 GeV), and Swift-XRT (2-10 keV). The data were taken from December 2011 through January 2012 and show a strong detection in all three wavebands. During this period VERITAS obtained 24.9 hours of quality selected livetime data in which LS I +61 303 was detected at a statistical sig- nificance of 11.9 sigma. These TeV observations show evidence for nightly variability in the TeV regime at a post-trial significance of 3.6 sigma. The combination of the simultaneously obtained TeV and X-ray fluxes do not demonstrate any evidence for a correlation between emission in the two bands. For the first time since the launch of the Fermi satellite in 2008, this TeV detection allows the construction of a detailed MeV-TeV spectral energy distribution from LS I +61 303. This spectrum shows a distinct cutoff in emission near 4 GeV, with emission seen by the VERITAS observations following a simple power-law above 200 GeV. This feature in the spectrum of LS I +61 303, obtained from overlapping observations with Fermi-LAT and VERITAS, may indicate that there are two distinct populations of accelerated particles producing the GeV and TeV emission., Accepted for Publication in ApJ

Published
2013
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17. Discovery of TeV Gamma-ray Emission from CTA 1 by VERITAS

Author

A. N. Otte, G. H. Sembroski, M. P. Connolly, E. Aliu, T. J. N. Nelson, R. Welsing, K. Lee, L. Ciupik, M. Theiling, P. Moriarty, Eric V. Gotthelf, Geza Gyuk, N. Karlsson, J. P. Finley, Wei Cui, Q. Feng, Gernot Maier, T. C. Weekes, I. Telezhinsky, Jamie Holder, S. Thibadeau, D. Gall, Oleg Kargaltsev, A. O'Faolain de Bhroithe, H. Krawczynski, A. Furniss, N. Galante, S. P. Wakely, R. Mukherjee, R. A. Ong, E. Roache, R. Dickherber, H. Prokoph, S. Vincent, A. S. Madhavan, Wystan Benbow, Abraham D. Falcone, S. Griffin, G. Finnegan, A. W. Smith, Mallory S. E. Roberts, S. McArthur, C. Duke, B. Zitzer, P. T. Reynolds, P. Kaaret, K. Ragan, J. Tyler, F. Krennrich, Y. Khassen, M. Schroedter, A. Bouvier, Vikram V. Dwarkadas, M. Vivier, J. Grube, M. Beilicke, Manel Errando, D. Staszak, S. Federici, J. H. Buckley, P. Majumdar, J. S. Perkins, David Kieda, D. B. Saxon, E. Collins-Hughes, Luis C. Reyes, N. H. Park, David A. Williams, Patrick Slane, M. Orr, T. B. Humensky, T. Aune, S. Godambe, G. Hughes, T. Arlen, Lucy Fortson, A. Cesarini, John L. Quinn, Martin Pohl, J. Dumm, Vladimir Vassiliev, A. Varlotta, M. J. Lang, A. Weinstein, K. Tsurusaki, G. H. Gillanders, D. S. Hanna, G. Tešić, V. Bugaev, S. Archambault, and A. McCann

Subjects
catalog, gamma-rays: stars, Photon, Astrophysics::High Energy Astrophysical Phenomena, supernova remnant cta-1, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar wind nebula, atmospheric cherenkov telescopes, Pulsar, Observatory, hess j1825-137, evolution, 0103 physical sciences, pulsations, crab-nebula, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, pulsars: individual (psr j0007+7303), 010308 nuclear & particles physics, Gamma ray, Astronomy and Astrophysics, x-rays: individual (rx j0007.0+7303), astronomy, supernovae: individual (g119.5+10.2), x-ray, Space and Planetary Science, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, pulsar-wind nebulae, Fermi Gamma-ray Space Telescope
Abstract

We report the discovery of TeV gamma-ray emission coincident with the shell-type radio supernova remnant (SNR) CTA 1 using the VERITAS gamma-ray observatory. The source, VER J0006+729, was detected as a 6.5 standard deviation excess over background and shows an extended morphology, approximated by a two-dimensional Gaussian of semi-major (semi-minor) axis 0.30 degree (0.24 degree) and a centroid 5' from the Fermi gamma-ray pulsar PSR J0007+7303 and its X-ray pulsar wind nebula (PWN). The photon spectrum is well described by a power-law dN/dE = N_0 (E/3 TeV)^(-\Gamma), with a differential spectral index of \Gamma = 2.2 +- 0.2_stat +- 0.3_sys, and normalization N_0 = (9.1 +- 1.3_stat +- 1.7_sys) x 10^(-14) cm^(-2) s^(-1) TeV^(-1). The integral flux, F_\gamma = 4.0 x 10^(-12) erg cm^(-2) s^(-1) above 1 TeV, corresponds to 0.2% of the pulsar spin-down power at 1.4 kpc. The energetics, co-location with the SNR, and the relatively small extent of the TeV emission strongly argue for the PWN origin of the TeV photons. We consider the origin of the TeV emission in CTA 1., Comment: 10 pages, 9 figures, accepted for publication in ApJ

Published
2012
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18. Search for a correlation between very-high-energy gamma rays and giant radio pulses in the Crab pulsar

Author

Matthias Beilicke, J. P. Dumm, Martin Pohl, G. Tešić, Q. Feng, V. Bugaev, T. Aune, A. Varlotta, R. Dickherber, T. B. Humensky, T. J. N. Nelson, S. Thibadeau, A. McCann, M. P. Connolly, Maxim Lyutikov, R. G. Wagner, Henric Krawczynski, E. Aliu, A. J.R. Weinstein, I. Telezhinsky, Jamie Holder, F. Krennrich, H. Prokoph, S. Vincent, L. C. Reyes, K. Lee, Sinéad M. Griffin, D. B. Saxon, Karen Byrum, D. S. Hanna, N. H. Park, Lucy Fortson, D. Staszak, K. Tsurusaki, M. Theiling, T. C. Arlen, K. Ragan, Gareth Hughes, Amy Furniss, P. Kaaret, M. Schroedter, B. Zitzer, E. Collins-Hughes, Gernot Maier, M. J. Lang, G. H. Gillanders, S. Godambe, S. P. Wakely, G. H. Sembroski, Daniel Gall, R. Welsing, A. N. Otte, Matthew R. Orr, L. Ciupik, A. Cesarini, R. A. Ong, V. Kondratiev, David A. Williams, John L. Quinn, A. Bouvier, J. H. Buckley, A. D. Falcone, J. P. Finley, M. Vivier, T. C. Weekes, S. LeBohec, David Kieda, S. McArthur, Y. Khassen, P. T. Reynolds, Geza Gyuk, Pratik Majumdar, S. Archambault, Reshmi Mukherjee, Wystan Benbow, J. S. Perkins, P. Moriarty, Nicola Galante, J. Grube, N. Karlsson, G. Finnegan, A. W. Smith, A. S Madhavan, C. Duke, E. Roache, G. D. Şentürk, H. Huan, A. O'Faolain de Bhroithe, S. Federici, and Wei Cui

Subjects
High energy, nebula, pulsars: individual: b0531+21, Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, Arrival time, law.invention, Radio telescope, Telescope, law, Time windows, 0103 physical sciences, emission, photons, rays: stars, geminga, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), model, 010308 nuclear & particles physics, Crab Pulsar, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, telescopes, universe, Space and Planetary Science, range, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays ($E_{\gamma} >$ 150 GeV) and Giant Radio Pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15366 GRPs were recorded during 11.6 hours of simultaneous observations, which were made across four nights in December 2008 and in November and December 2009. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. In total, 8 different time windows with durations ranging from 0.033 ms to 72 s were positioned at three different locations relative to the GRP to search for enhanced gamma-ray emission which lagged, led, or was concurrent with, the GRP event. Further, we performed separate searches on main pulse GRPs and interpulse GRPs and on the most energetic GRPs in our data sample. No significant enhancement of pulsed VHE emission was found in any of the preformed searches. We set upper limits of 5-10 times the average VHE flux of the Crab pulsar on the flux simultaneous with interpulse GRPs on single-rotation-period time scales. On $\sim$8-second time scales around interpulse GRPs, we set an upper limit of 2-3 times the average VHE flux. Within the framework of recent models for pulsed VHE emission from the Crab pulsar, the expected VHE-GRP emission correlations are below the derived limits., Comment: 12 pages, 12 figures, To appear in The Astrophysical Journal

Published
2012
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19. VERITAS Observations of the Nova in V407 Cygni

Author

H. J. Rose, A. Cesarini, John L. Quinn, Gernot Maier, S. Griffin, M. Orr, A. Varlotta, Martin Pohl, D. Staszak, G. Hughes, E. Aliu, S. P. Wakely, J. Dumm, S. Vincent, K. Lee, D. S. Hanna, G. Tešić, M. Theiling, T. Weisgarber, S. M. Bradbury, A. Cannon, P. Kaaret, J. P. Finley, S. Godambe, M. Kertzman, T. B. Humensky, T. C. Weekes, K. Tsurusaki, Geza Gyuk, Dirk Pandel, M. J. Lang, S. Thibadeau, H. Krawczynski, V. Bugaev, T. Arlen, N. Galante, J. Ruppel, M. Schroedter, Vikram V. Dwarkadas, B. Zitzer, G. Finnegan, J. Grube, A. W. Smith, Manel Errando, S. Archambault, Lucy Fortson, G. H. Sembroski, M. Vivier, Abraham D. Falcone, C. Duke, M. Beilicke, Wystan Benbow, J. H. Buckley, David A. Williams, R. Welsing, D. B. Saxon, H. Huan, N. H. Park, K. Ragan, S. McArthur, I. Telezhinsky, David Kieda, Paul D. Nuñez, A. McCann, Wei Cui, Jamie Holder, P. Majumdar, E. Roache, P. Moriarty, J. E. Ward, G. Decerprit, C. Skole, A. Weinstein, H. Prokoph, J. Tyler, Karen Byrum, R. A. Ong, A. N. Otte, M. P. Connolly, Q. Feng, T. Aune, F. Krennrich, J. S. Perkins, E. Collins-Hughes, L. Ciupik, J. Millis, A. Bouvier, P. T. Reynolds, D. Gall, R. Mukherjee, Luis C. Reyes, N. Karlsson, A. Furniss, R. Dickherber, and Y. Khassen

Subjects
High energy, blast wave, FOS: Physical sciences, Radiation imaging, Flux, array, Astrophysics, galactic plane, 01 natural sciences, law.invention, Telescope, law, 0103 physical sciences, novae, cataclysmic variables, 010306 general physics, 010303 astronomy & astrophysics, Zenith, white dwarfs, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma rays: general, Nova (laser), gamma-ray emission, Astrophysics - Astrophysics of Galaxies, rs-ophiuchi, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), cherenkov telescopes, Astrophysics - High Energy Astrophysical Phenomena, 2006 outburst, discovery
Abstract

We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles, due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 \times 10^(-12) erg cm^(-2) s^(-1) (at the 95% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova., 17 pages, 4 figures, accepted for publication in ApJ

Published
2012
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20. Discovery of High-energy and Very High Energy Gamma-ray Emission from the Blazar RBS 0413

Author

D. Gall, M. P. Connolly, R. Mukherjee, G. H. Sembroski, S. McArthur, T. B. Humensky, S. Archambault, S. Griffin, P. Fortin, H. J. Rose, A. Pichel, P. T. Reynolds, J. E. Ward, A. Cesarini, A. N. Otte, John L. Quinn, A. S. Madhavan, Wystan Benbow, A. Varlotta, P. Majumdar, I. Telezhinsky, J. Grube, R. A. Ong, Manel Errando, Jamie Holder, A. Bouvier, M. J. Lang, M. Theiling, J. P. Finley, S. M. Bradbury, K. Ragan, Wei Cui, S. Thibadeau, T. Aune, Markus Böttcher, T. C. Weekes, Abraham D. Falcone, G. Decerprit, L. C. Reyes, A. McCann, H. Prokoph, E. Roache, N. Palma, Geza Gyuk, G. Tešić, E. Aliu, D. Horan, J. Ruppel, L. Ciupik, Gareth Hughes, M. Kertzman, B. Zitzer, T. Weisgarber, K. Lee, D. S. Hanna, V. Bugaev, A. Weinstein, M. Vivier, David A. Williams, H. Krawczynski, K. Tsurusaki, S. Godambe, T. Arlen, Lucy Fortson, Martin Pohl, J. Dumm, Keith Hawkins, Karen Byrum, M. Schroedter, M. Beilicke, David Kieda, J. H. Buckley, J. S. Perkins, E. Collins-Hughes, F. Krennrich, M. Orr, Q. Feng, A. Cannon, P. Kaaret, D. B. Saxon, N. H. Park, Gernot Maier, S. P. Wakely, N. Galante, G. Finnegan, A. W. Smith, G. D. Şentürk, H. Huan, Paolo De Coppi, P. Moriarty, A. Furniss, D. Staszak, R. Dickherber, Y. Khassen, and N. Karlsson

Subjects
catalog, Astrophysics::High Energy Astrophysical Phenomena, bl-lacertae objects, Flux, FOS: Physical sciences, Astrophysics, swift ultraviolet/optical telescope, bright blazars, 7. Clean energy, 01 natural sciences, law.invention, Telescope, law, gamma rays: galaxies, 0103 physical sciences, bl lacertae objects: individual (rbs 0413-ver j0319+187), Blazar, Nuclear Experiment, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), model, 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, lac objects, Synchrotron, radiation, large-area telescope, Crab Nebula, mission, 13. Climate action, Space and Planetary Science, active galactic nuclei, Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object, Fermi Gamma-ray Space Telescope
Abstract

We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high-energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE gamma rays from RBS 0413 with a statistical significance of 5.5 standard deviations (sigma) and a gamma-ray flux of (1.5 \pm 0.6stat \pm 0.7syst) \times 10^(-8) photons m^(-2) s^(-1) (\sim 1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 \pm 0.68stat \pm 0.30syst. Contemporaneous observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope detected HE gamma rays from RBS 0413 with a statistical significance of more than 9 sigma, a power-law photon index of 1.57 \pm 0.12stat +0.11sys -0.12sys and a gamma-ray flux between 300 MeV and 300 GeV of (1.64 \pm 0.43stat +0.31sys -0.22sys) \times 10^(-5) photons m^(-2) s^(-1). We present the results from Fermi-LAT and VERITAS, including a spectral energy distribution modeling of the gamma-ray, quasi-simultaneous X-ray (Swift-XRT), ultraviolet (Swift-UVOT) and R-band optical (MDM) data. We find that, if conditions close to equipartition are required, both the combined synchrotron self-Compton/external-Compton and the lepto-hadronic models are preferred over a pure synchrotron self-Compton model., 14 pages, 3 figures, accepted to ApJ, corresponding author: G. D. Senturk

Published
2012
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21. VERITAS deep observations of the dwarf spheroidal galaxy Segue 1

Author

A. McCann, I. Telezhinsky, R. A. Ong, Jamie Holder, T. Arlen, G. Teić, Philip Kaaret, A. S. Madhavan, Wystan Benbow, S. Vincent, N. Galante, G. D. Entürk, A. Bouvier, G. H. Sembroski, S. McArthur, G. Finnegan, A. W. Smith, S. M. Bradbury, Gernot Maier, M. P. Connolly, S. P. Wakely, Abraham D. Falcone, A. Varlotta, T. Aune, J. Grube, A. Cannon, E. Roache, H. Huan, Matthew R. Orr, R. Dickherber, Manel Errando, Daniel Gall, Karen Byrum, K. Ragan, S. Thibadeau, J. H. Buckley, E. Collins-Hughes, M. Kertzman, Lucy Fortson, J. S. Perkins, H. J. Rose, G. Decerprit, V. Bugaev, Q. Feng, P. Moriarty, M. Vivier, M. Beilicke, M. Schroedter, David A. Williams, Y. Khassen, T. Weisgarber, D. Staszak, J. E. Ward, S. Archambault, Reshmi Mukherjee, T. B. Humensky, A. Furniss, Francesc Ferrer, Geza Gyuk, D. B. Saxon, A. Cesarini, John L. Quinn, B. Zitzer, P. T. Reynolds, N. H. Park, Henric Krawczynski, L. Ciupik, P. Majumdar, E. Aliu, K. Tsurusaki, Jodi Christiansen, C. Skole, D. Hanna, Martin Pohl, S. Godambe, J. Dumm, K. Lee, L. C. Reyes, Vladimir Vassiliev, N. Karlsson, J. P. Finley, T. C. Weekes, Wei Cui, H. Prokoph, R. G. Wagner, David Kieda, M. Theiling, J. Ruppel, Amanda Weinstein, A. N. Otte, Frank Krennrich, Sinéad M. Griffin, and Gareth Hughes

Subjects
Nuclear and High Energy Physics, Astrophysics::High Energy Astrophysical Phenomena, Dwarf galaxy problem, cosmic-rays, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, dark-matter annihilation, 01 natural sciences, local group, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, upper limits, ddc:530, 010303 astronomy & astrophysics, Light dark matter, galactic-center, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Hot dark matter, Institut für Physik und Astronomie, Astronomy, Segue, gamma-ray emission, Galaxy, Dwarf spheroidal galaxy, Dark matter halo, large-area telescope, cherenkov telescopes, Astrophysics - High Energy Astrophysical Phenomena, magic telescope, empirical-models
Abstract

The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant $\gamma$-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are $\mathrm{^{95% CL} \lesssim 10^{-23} cm^{3} s^{-1}}$, improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of two for dark matter particle masses $\mathrm{m_{\chi}\gtrsim 300 GeV}$. The lower limits on the decay lifetime are at the level of $\mathrm{\tau^{95% CL} \gtrsim 10^{24} s}$. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario., Comment: Added recently published erratum at the end of the original article

Published
2012
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22. Multiwavelength observations of the AGN 1ES 0414+009 with veritas, FERMI-LAT, SWIFT-XRT, AND MDM

Author

E. Aliu, S. Archambault, T. Arlen, T. Aune, M. Beilicke, W. Benbow, M. Böttcher, A. Bouvier, V. Bugaev, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, J. Dumm, M. Errando, A. Falcone, S. Federici, Q. Feng, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, C. M. Hui, A. Imran, O. Jameil, P. Kaaret, N. Karlsson, M. Kertzman, J. Kerr, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, K. Lee, A. S. Madhavan, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, T. Nelson, A. O'Faoláin de Bhróithe, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, A. Pichel, M. Pohl, J. Quinn, K. Ragan, P. T. Reynolds, E. Roache, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, M. Stroh, I. Telezhinsky, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, V. V. Vassiliev, M. Vivier, S. P. Wakely, J. E. Ward, A. Weinstein, R. Welsing, D. A. Williams, and B. Zitzer

Subjects
stars, Photon, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, blazars, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, telescope, 01 natural sciences, Power law, purl.org/becyt/ford/1 [https], gamma-ray astronomy, 0103 physical sciences, gamma rays: galaxies, emission, bl lacertae objects: individual (1es 0414+009, erj0416+011), Nuclear Experiment, 010303 astronomy & astrophysics, Cherenkov radiation, Physics, search, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], sample, Astronomía, Crab Nebula, individual (1ES 0414+009, VERJ0416+011) [BL Lacertae objects], Space and Planetary Science, bl lacertae object, galaxies [gamma rays], Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, discovery, Fermi Gamma-ray Space Telescope, BL Lac object
Abstract

We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between January 2008 and February 2011, resulting in 56.2 hours of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4 sigma) above the background. The source flux, showing no evidence for variability, is measured as 5.2 +/- 1.1_stat +/- 2.6_sys * 10^-12 photons cm^-2 s^-1 above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with an photon index of Gamma 3.4 +/- 0.5_stat +/- 0.3_sys and a flux normalization of 1.6 +/- 0.3_stat +/- 0.8_sys * 10^-11 photons cm^-2 s^-1 at 300 GeV. We also present multiwavelength results taken in the optical (MDM), X-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data., Accepted for publication in The Astrophysical Journal

Published
2012
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23. VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT Blazars

Author

S. McArthur, Martin Pohl, T. Aune, J. Dumm, A. O'Faolain de Bhroithe, H. Krawczynski, D. B. Saxon, S. Griffin, A. N. Otte, D. S. Hanna, S. Thibadeau, Jason X. Prochaska, N. H. Park, R. A. Ong, Markus Böttcher, D. Horan, A. Bouvier, F. Krennrich, J. H. Buckley, M. Orr, Wystan Benbow, L. Ciupik, P. T. Reynolds, Gernot Maier, K. Ragan, S. P. Wakely, H. Prokoph, V. V. Vassiliev, N. Galante, S. Vincent, Abraham D. Falcone, D. Gall, David A. Williams, R. Mukherjee, J. S. Perkins, A. Pichel, E. Collins-Hughes, P. Fortin, T. Arlen, M. P. Connolly, G. Finnegan, A. McCann, B. Zitzer, A. Cesarini, A. S Madhavan, C. Duke, Q. Feng, John L. Quinn, E. Aliu, A. Varlotta, Geza Gyuk, Lucy Fortson, H. Huan, K. Lee, Pratik Majumdar, J. Grube, Manel Errando, Kyle F. Kaplan, I. Telezhinsky, Jamie Holder, J. P. Finley, E. Roache, A. Furniss, L. C. Reyes, T. C. Weekes, R. Dickherber, G. H. Sembroski, R. Welsing, D. Staszak, Michele Fumagalli, Y. Khassen, P. Kaaret, N. Karlsson, S. Federici, P. Moriarty, Wei Cui, S. Archambault, M. Theiling, G. Tešić, T. J. N. Nelson, V. Bugaev, A. Weinstein, M. Vivier, M. Beilicke, David Kieda, K. Tsurusaki, S. Godambe, Aliu, E, Archambault, S, Arlen, T, Aune, T, Beilicke, M, Benbow, W, Bottcher, M, Bouvier, A, Buckley, J, Bugaev, V, Cesarini, A, Ciupik, L, Collins-Hughes, E, Connolly, M, Cui, W, Dickherber, R, Duke, C, Dumm, J, Errando, M, Falcone, A, Federici, S, Feng, Q, Finley, J, Finnegan, G, Fortson, L, Furniss, A, Galante, N, Gall, D, Godambe, S, Griffin, S, Grube, J, Gyuk, G, Hanna, D, Holder, J, Huan, H, Kaaret, P, Karlsson, N, Khassen, Y, Kieda, D, Krawczynski, H, Krennrich, F, Lee, K, Madhavan, A, Maier, G, Majumdar, P, Mcarthur, S, Mccann, A, Moriarty, P, Mukherjee, R, Nelson, T, De Bhroithe, A, Ong, R, Orr, M, Otte, A, Park, N, Perkins, J, Pichel, A, Pohl, M, Prokoph, H, Quinn, J, Ragan, K, Reyes, L, Reynolds, P, Roache, E, Saxon, D, Sembroski, G, Staszak, D, Telezhinsky, I, Tesic, G, Theiling, M, Thibadeau, S, Tsurusaki, K, Varlotta, A, Vassiliev, V, Vincent, S, Vivier, M, Wakely, S, Weekes, T, Weinstein, A, Welsing, R, Williams, D, Zitzer, B, Fortin, P, Horan, D, Fumagalli, M, Kaplan, K, and Prochaska, J

Subjects
Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 7. Clean energy, law.invention, purl.org/becyt/ford/1 [https], Telescope, law, 0103 physical sciences, gamma rays: galaxie, Astrophysics::Solar and Stellar Astrophysics, Blazar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, general [BL Lacertae objects], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Institut für Physik und Astronomie, Spectral density, Astronomy and Astrophysics, BL Lacertae objects: general, purl.org/becyt/ford/1.3 [https], Synchrotron, Redshift, Astronomía, Extragalactic background light, Space and Planetary Science, Sky, galaxies [gamma rays], Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Fermi Gamma-ray Space Telescope
Abstract

We report on VERITAS very high energy (VHE; E > 100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV upper limits are presented, along with contemporaneous Fermi observations and non-concurrent Swift UVOT and X-Ray Telescope data. The blazar broadband spectral energy distributions (SEDs) are assembled and modeled with a single-zone synchrotron self-Compton model. The SED built for each of the six blazars shows a synchrotron peak bordering between the intermediate- and high-spectrum-peak classifications, with four of the six resulting in particle-dominated emission regions. Fil: Aliu, E.. Columbia University; Estados Unidos Fil: Archambault, S.. McGill University; Canadá Fil: Arlen, T.. University of California; Estados Unidos Fil: Aune, E.. University of California; Estados Unidos Fil: Beilicke, M.. University of Washington; Estados Unidos Fil: Benbow, W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos Fil: Bottcher, M.. Ohio University; Estados Unidos Fil: Bouvier, A.. University of California; Estados Unidos Fil: Buckley, J. H.. University of Washington; Estados Unidos Fil: Bugaev, V.. University of Washington; Estados Unidos Fil: Cesarini, A.. National University of Ireland Galway; Irlanda Fil: Ciupik, L.. Adler Planetarium and Astronomy Museum; Estados Unidos Fil: Collin Hughes, E.. University College Dublin; Irlanda Fil: Connolly, M. P.. National University of Ireland Galway; Irlanda Fil: Cui, W.. Purdue University; Estados Unidos Fil: Dickherber, R.. University of Washington; Estados Unidos Fil: Duke, C.. Grinnell College; Estados Unidos Fil: Dumm, J.. University Of Minnesota; Estados Unidos Fil: Errando, M.. Columbia University; Estados Unidos Fil: Falcone, A.. University of Pennsylvania; Estados Unidos Fil: Federici, S.. Desy; Alemania Fil: Feng, Q.. Purdue University; Estados Unidos Fil: Finley, J. P.. Purdue University; Estados Unidos Fil: Finnegan, G.. University of Utah; Estados Unidos Fil: Fortson, L.. University Of Minnesota; Estados Unidos Fil: Furniss, A.. University of California; Estados Unidos Fil: Galante, N.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos Fil: Gall, D.. University of Iowa; Estados Unidos Fil: Godambe, S.. University of Utah; Estados Unidos Fil: Griffin, S.. McGill University; Canadá Fil: Pichel, Ana Carolina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: The Veritas Collaboration.

Published
2012
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24. Constraints on Cosmic Rays, Magnetic Fields, and Dark Matter from Gamma-Ray Observations of the Coma Cluster of Galaxies with VERITAS and Fermi

Author

T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, J. Dumm, A. Falcone, S. Federici, Q. Feng, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, G. Gyuk, J. Holder, H. Huan, G. Hughes, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, K. Lee, A. S Madhavan, G. Maier, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, T. Nelson, A. O’Faoláin de Bhróit, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, M. Pohl, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, C. Skole, A. W. Smith, I. Telezhinsky, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, M. Vivier, S. P. Wakely, J. E. Ward, A. Weinstein, R. Welsing, D. A. Williams, B. Zitzer, C. Pfrommer, and A. Pinzke

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Dark matter, nonthermal emission, FOS: Physical sciences, Coma (optics), Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies: clusters: individual (coma (aco 1656)), magnetic fields, dark matter, large-scale structure, shock-waves, atmospheric cherenkov telescopes, diffuse radio-emission, cosmic rays, all-sky survey, Coma Cluster, upper limits, galactic-center, Galaxy cluster, Cherenkov radiation, gamma rays: galaxies: clusters, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Institut für Physik und Astronomie, Astronomy and Astrophysics, source catalog, Galaxy, x-ray, galaxies: clusters: general, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Fermi Gamma-ray Space Telescope
Abstract

Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated, suggesting that clusters may also be sources of very high-energy (VHE; E>100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cherenkov telescopes, with complementing Fermi-LAT observations at GeV energies. No significant gamma-ray emission from the Coma cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5)*10^-8\ ph. m^-2 s^-1 (VERITAS, >220 GeV} and ~2*10^-6 ph. m^-2 s^-1 (Fermi, 1-3 GeV), respectively. We use the gamma-ray upper limits to constrain CRs and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be < 16% from VERITAS data and < 1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be, ApJ in press

Published
2012
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25. VERITASDETECTION OFγ-RAY FLARING ACTIVITY FROM THE BL LAC OBJECT 1ES 1727+502 DURING BRIGHT MOONLIGHT OBSERVATIONS

Author

S. Vincent, A. Varlotta, A. McCann, P. Kaaret, J. D. Eisch, R. Mukherjee, A. Weinstein, Geza Gyuk, E. Pueschel, Maria Krause, David Kieda, Daniel Nieto, M. J. Lang, John L. Quinn, I. Telezhinsky, Jamie Holder, T. B. Humensky, Sinéad M. Griffin, A. Bouvier, F. Krennrich, A. O Faoláin De Bhróithe, L. C. Reyes, B. Zitzer, J. Biteau, K. Meagher, A. Archer, M. Kertzman, J. Grube, Manel Errando, S. Kumar, A. Wilhelm, Y. Khassen, Wystan Benbow, R. A. Ong, Wei Cui, J. V. Tucci, J. Tyler, Gernot Maier, A. Popkow, S. T. Griffiths, J. V. Cardenzana, E. Roache, A. W. Smith, Z. D. Hughes, Marcos Santander, Martin Pohl, C. A. Johnson, David A. Williams, Xuhui Chen, Gordon T. Richards, J. Dumm, L. Ciupik, P. Fortin, D. Staszak, G. H. Sembroski, Ralph Bird, R. Welsing, G. H. Gillanders, Hugh Dickinson, Abraham D. Falcone, Karlen Shahinyan, P. Kar, Matteo Cerruti, Q. Feng, P. T. Reynolds, N. Håkansson, Henrike Fleischhack, Amy Furniss, J. P. Finley, A. N. Otte, M. P. Connolly, Matthias Beilicke, S. P. Wakely, P. Moriarty, S. McArthur, K. Ragan, Lucy Fortson, N. H. Park, J. Millis, D. S. Hanna, V. Bugaev, S. Archambault, H. Prokoph, and ~

Subjects
Source catalog, Moonlight, Radiation mechanisms: non-thermal, Smithsonian institution, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Galactic nuclei, Self Compton model, 7. Clean energy, Blazar, Lacertae objects, Physics, Large area telescope, TEV BLAZARS, Crab nebula, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, FERMI ERA, Astronomy and Astrophysics, Galaxies: active, BL Lacertae objects: individual (1ES 1727+502), Gamma rays: galaxies, Space and Planetary Science, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, Host galaxies, Spectral energy distribution, BL Lac object
Abstract

During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHE, $E>100$ GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations with the VERITAS telescopes in the standard configuration are performed only with a moon illumination less than 35$\%$ of full moon. Since 2012, the VERITAS collaboration has implemented a new observing mode under bright moonlight, by either reducing the voltage applied to the PMTs (reduced-high-voltage configuration, RHV), or by utilizing UV-transparent filters. While these operating modes result in lower sensitivity and increased energy thresholds, the extension of the available observing time is useful for monitoring variable sources such as blazars and sources requiring spectral measurements at the highest energies. In this paper we report the detection of $\gamma$-ray flaring activity from the BL Lac object 1ES 1727+502 during RHV observations. This detection represents the first evidence of VHE variability from this blazar. The integral flux is $(1.1\pm0.2)\times10^{-11}\mathrm{cm^{-2}s^{-1}}$ above 250 GeV, which is about five times higher than the low-flux state. The detection triggered additional \veritas\ observations during standard dark-time. Multiwavelength observations with the FLWO 48" telescope, and the Swift and Fermi satellites are presented and used to produce the first spectral energy distribution (SED) of this object during $\gamma$-ray flaring activity. The SED is then fitted with a standard synchrotron-self-Compton model, placing constraints on the properties of the emitting region and of the acceleration mechanism at the origin of the relativistic particle population in the jet., Comment: 11 pages, 3 figures, accepted for publication in ApJ

Published
2015
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26. RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

Author

M. P. Connolly, T. Arlen, Anthony C. S. Readhead, Luis C. Reyes, Alan P. Marscher, Lucy Fortson, Emilia Järvelä, Q. Feng, Martin Pohl, T. J. N. Nelson, J. Grube, Manel Errando, J. Dumm, Matthew L. Lister, Joseph L. Richards, Wystan Benbow, Alexander B. Pushkarev, L. Ciupik, D. S. Hanna, A. Pichel, G. Tešić, K. Ragan, R. A. Ong, N. Karlsson, A. Bouvier, Yuri Y. Kovalev, S. Vincent, B. Zitzer, R. C. Walker, A. Furniss, T. Aune, R. Dickherber, J. S. Perkins, Walter Max-Moerbeck, E. Nieppola, M. Beilicke, S. Federici, P. T. Reynolds, J. H. Buckley, Nicholas R. MacDonald, Y. Khassen, V. Bugaev, Paul S. Smith, David Kieda, Geza Gyuk, A. Weinstein, F. Krennrich, Wei Cui, G. H. Sembroski, D. Gall, R. Welsing, R. Mukherjee, H. Prokoph, T. B. Humensky, Anne Lähteenmäki, I. Telezhinsky, Jamie Holder, K. Tsurusaki, E. Roache, Abraham D. Falcone, M. Theiling, J. P. Finley, T. C. Weekes, David A. Williams, Mark Gurwell, Gernot Maier, S. Griffin, A. Cesarini, John L. Quinn, A. Varlotta, S. P. Wakely, M. Schroedter, D. B. Saxon, N. H. Park, P. Kaaret, M. Orr, Talvikki Hovatta, Svetlana G. Jorstad, M. Kertzman, A. O'Faolain de Bhroithe, H. Krawczynski, P. Moriarty, N. Galante, G. Finnegan, Merja Tornikoski, D. Staszak, Anne Lähteenmäki Group, Aalto-yliopisto, and Aalto University

Subjects
multiwavelength observations, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, education, galaxies: active, blazars, galaxies: individual (bl lacertae, ver j2202+422), FOS: Physical sciences, Astrophysics, swift ultraviolet/optical telescope, 01 natural sciences, law.invention, purl.org/becyt/ford/1 [https], law, individual (BL Lacertae, VER J2202+422) [galaxies], gamma rays: galaxies, 0103 physical sciences, high-frequencies, Astrophysics::Solar and Stellar Astrophysics, pks 1222+216, individual: BL Lacertae VER J2202+422 [galaxies], Blazar, 010303 astronomy & astrophysics, Very Long Baseline Array, relativistic jets, High Energy Astrophysical Phenomena (astro-ph.HE), polarimetric observations, Physics, Superluminal motion, radio-sources, variability, 010308 nuclear & particles physics, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, Optical polarization, purl.org/becyt/ford/1.3 [https], Light curve, Astronomía, Crab Nebula, Space and Planetary Science, active [galaxies], galaxies [gamma rays], active galactic nuclei, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Flare
Abstract

We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6-minute exposure, when the integral flux above 200 GeV reached $(3.4\pm0.6) \times 10^{-6} \;\text{photons}\;\text{m}^{-2}\text{s}^{-1}$, roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be $13\pm4$ minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of $3.6\pm 0.4$, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. Contemporaneous radio observations of the source with the Very Long Baseline Array (VLBA) revealed the emergence of a new, superluminal component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results., Comment: Accepted for publication in The Astrophysical Journal

Published
2012
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27. Long-term TeV and X-ray Observations of the Gamma-ray Binary HESS J0632+057

Author

VERITAS Collaboration, Aliu, E., Archambault, S., Aune, T., Behera, B., Beilicke, M., Benbow, W., Berger, K., Bird, R., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cerruti, M., Chen, X., Ciupik, L., Connolly, M. P., Cui, W., Duke, C., Dumm, J., Errando, M., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Fortin, P., Fortson, L., Furniss, A., Galante, N., Gillanders, G. H., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Hanna, D., Holder, J., Hughes, G., Humensky, T. B., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Madhavan, A. S, Maier, G., Majumdar, P., McCann, A., Moriarty, P., Mukherjee, R., Nieto, D., de Bhr��ithe, A. O'Faol��in, Ong, R. A., Otte, A. N., Park, N., Perkins, J. S., Pohl, M., Popkow, A., Prokoph, H., Quinn, J., Ragan, K., Rajotte, J., Reyes, L. C., Reynolds, P. T., Richards, G. T., Roache, E., Rousselle, J., Sembroski, G. H., Sheidaei, F., Skole, C., Smith, A. W., Staszak, D., Stroh, M., Telezhinsky, I., Theiling, M., Tucci, J. V., Tyler, J., Varlotta, A., Vincent, S., Wakely, S. P., Weinstein, A., Welsing, R., Williams, D. A., Zajczyk, A., Zitzer, B., Collaboration, H. E. S. S., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Akhperjanian, A. G., Ang��ner, E., Anton, G., Balenderan, S., Balzer, A., Barnacka, A., Becherini, Y., Tjus, J. Becker, Bernl��hr, K., Birsin, E., Bissaldi, E., Biteau, J., B��ttcher, M., Boisson, C., Bolmont, J., Bordas, P., Brucker, J., Brun, F., Brun, P., Bulik, T., Carrigan, S., Casanova, S., Chadwick, P. M., Chalme-Calvet, R., Chaves, R. C. G., Cheesebrough, A., Chr��tien, M., Colafrancesco, S., Cologna, G., Conrad, J., Couturier, C., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., deWilt, P., Dickinson, H. J., Djannati-Ata��, A., Domainko, W., Drury, L. O'C., Dubus, G., Dutson, K., Dyks, J., Dyrda, M., Edwards, T., Egberts, K., Eger, P., Espigat, P., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fernandez, D., Fiasson, A., Fontaine, G., Forster, A., F����ling, M., Gajdus, M., Gallant, Y. A., Garrigoux, T., Giavitto, G., Giebels, B., Glicenstein, J. F., Grondin, M. -H., Grudzi��ska, M., H��ffner, S., Hahn, J., Harris, J., Heinzelmann, G., Henri, G., Hermann, G., Hervet, O., Hillert, A., Hinton, J. A., Hofmann, W., Hofverberg, P., Holler, M., Horns, D., Jacholkowska, A., Jahn, C., Jamrozy, M., Janiak, M., Jankowsky, F., Jung, I., Kastendieck, M. A., Katarzy��ski, K., Katz, U., Kaufmann, S., Kh��lifi, B., Kieffer, M., Klepser, S., Klochkov, D., Klu��niak, W., Kneiske, T., Kolitzus, D., Komin, Nu., Kosack, K., Krakau, S., Krayzel, F., Kr��ger, P. P., Laffon, H., Lamanna, G., Lefaucheur, J., Lemi��re, A., Lemoine-Goumard, M., Lenain, J. -P., Lennarz, D., Lohse, T., Lopatin, A., Lu, C. -C., Marandon, V., Marcowith, A., Marx, R., Maurin, G., Maxted, N., Mayer, M., McComb, T. J. L., M��hault, J., Menzler, U., Meyer, M., Moderski, R., Mohamed, M., Moulin, E., Murach, T., Naumann, C. L., de Naurois, M., Niemiec, J., Nolan, S. J., Oakes, L., Ohm, S., Wilhelmi, E. de On��a, Opitz, B., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Arribas, M. Paz, Pekeur, N. W., Pelletier, G., Perez, J., Petrucci, P. -O., Peyaud, B., Pita, S., Poon, H., P��hlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Raue, M., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Rob, L., Romoli, C., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Sahakian, V., Sanchez, D. A., Santangelo, A., Schlickeiser, R., Sch��ssler, F., Schulz, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Sol, H., Spengler, G., Spies, F., Stawarz, ��., Steenkamp, R., Stegmann, C., Stinzing, F., Stycz, K., Sushch, I., Szostek, A., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tluczykont, M., Trichard, C., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Viana, A., Vincent, P., V��lk, H. J., Volpe, F., Vorster, M., Wagner, S. J., Wagner, P., Ward, M., Weidinger, M., Weitzel, Q., White, R., Wierzcholska, A., Willmann, P., W��rnlein, A., Wouters, D., Zacharias, M., Zdziarski, A. A., Zech, A., Zechlin, H. -S., H.E.S.S. Collaboration, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Astroparticules (ASTRO), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), HESS, Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), 24420530 - Böttcher, Markus, 10103449 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 12006653 - Venter, Christo, 12792322 - Vorster, Michael Johannes, 23909196 - Casanova, Sabrina, 24922986 - Sushch, Iurii, E., Aliu, S., Archambault, T., Aune, B., Behera, M., Beilicke, W., Benbow, K., Berger, R., Bird, A., Bouvier, J. H., Buckley, V., Bugaev, K., Byrum, M., Cerruti, X., Chen, L., Ciupik, M. P., Connolly, W., Cui, C., Duke, J., Dumm, M., Errando, A., Falcone, S., Federici, Q., Feng, J. P., Finley, P., Fortin, L., Fortson, A., Furni, N., Galante, G. H., Gillander, S., Griffin, S. T., Griffith, J., Grube, G., Gyuk, D., Hanna, J., Holder, G., Hughe, T. B., Humensky, P., Kaaret, M., Kertzman, Y., Khassen, D., Kieda, H., Krawczynski, F., Krennrich, M. J., Lang, A. S., Madhavan, G., Maier, P., Majumdar, A., Mccann, P., Moriarty, R., Mukherjee, D., Nieto, A., O’Faoláin de Bhróithe, R. A., Ong, A. N., Otte, N., Park, J. S., Perkin, M., Pohl, A., Popkow, H., Prokoph, J., Quinn, K., Ragan, J., Rajotte, L. C., Reye, P. T., Reynold, G. T., Richard, E., Roache, J., Rousselle, G. H., Sembroski, F., Sheidaei, C., Skole, A. W., Smith, D., Staszak, M., Stroh, I., Telezhinsky, M., Theiling, J. V., Tucci, J., Tyler, A., Varlotta, S., Vincent, S. P., Wakely, A., Weinstein, R., Welsing, D. A., William, A., Zajczyk, B., Zitzer, A., Abramowski, F., Aharonian, F., Ait Benkhali, A. G., Akhperjanian, E., Angüner, G., Anton, S., Balenderan, A., Balzer, A., Barnacka, Y., Becherini, J., Becker Tju, K., Bernlöhr, E., Birsin, Bissaldi, Elisabetta, J., Biteau, M., Böttcher, C., Boisson, J., Bolmont, P., Borda, J., Brucker, F., Brun, P., Brun, T., Bulik, S., Carrigan, S., Casanova, P. M., Chadwick, R., Chalme Calvet, R. C. G., Chave, A., Cheesebrough, M., Chrétien, S., Colafrancesco, G., Cologna, J., Conrad, C., Couturier, M., Dalton, M. K., Daniel, I. D., David, B., Degrange, C., Deil, P., Dewilt, H. J., Dickinson, A., Djannati Ataï, W., Domainko, Drury, L. O. ’. C., G., Dubu, K., Dutson, J., Dyk, M., Dyrda, T., Edward, K., Egbert, P., Eger, P., Espigat, C., Farnier, S., Fegan, F., Feinstein, M. V., Fernande, D., Fernandez, A., Fiasson, G., Fontaine, A., Förster, M., Füssling, M., Gajdu, Y. A., Gallant, T., Garrigoux, G., Giavitto, B., Giebel, J. F., Glicenstein, M. H., Grondin, M., Grudzińska, S., Häffner, J., Hahn, J., Harri, G., Heinzelmann, G., Henri, G., Hermann, O., Hervet, A., Hillert, J. A., Hinton, W., Hofmann, P., Hofverberg, M., Holler, D., Horn, A., Jacholkowska, C., Jahn, M., Jamrozy, M., Janiak, F., Jankowsky, I., Jung, M. A., Kastendieck, K., Katarzyński, U., Katz, S., Kaufmann, B., Khélifi, M., Kieffer, S., Klepser, D., Klochkov, W., Kluźniak, T., Kneiske, D., Kolitzu, Komin, N. u., K., Kosack, S., Krakau, F., Krayzel, P. P., Krüger, H., Laffon, G., Lamanna, J., Lefaucheur, A., Lemière, M., Lemoine Goumard, J. P., Lenain, D., Lennarz, T., Lohse, A., Lopatin, C. C., Lu, V., Marandon, A., Marcowith, R., Marx, G., Maurin, N., Maxted, M., Mayer, T. J. L., Mccomb, J., Méhault, U., Menzler, M., Meyer, R., Moderski, M., Mohamed, E., Moulin, T., Murach, C. L., Naumann, M., de Nauroi, J., Niemiec, S. J., Nolan, L., Oake, S., Ohm, E., de Oña Wilhelmi, B., Opitz, M., Ostrowski, I., Oya, M., Panter, R. D., Parson, M., Paz Arriba, N. W., Pekeur, G., Pelletier, J., Perez, P. O., Petrucci, B., Peyaud, S., Pita, H., Poon, G., Pühlhofer, M., Punch, A., Quirrenbach, S., Raab, M., Raue, A., Reimer, O., Reimer, M., Renaud, R., de los Reye, F., Rieger, L., Rob, C., Romoli, S., Rosier Lee, G., Rowell, B., Rudak, C. B., Rulten, V., Sahakian, D. A., Sanchez, A., Santangelo, R., Schlickeiser, F., Schüssler, A., Schulz, U., Schwanke, S., Schwarzburg, S., Schwemmer, H., Sol, G., Spengler, F., Spie, Ł., Stawarz, R., Steenkamp, C., Stegmann, F., Stinzing, K., Stycz, I., Sushch, A., Szostek, J. P., Tavernet, T., Tavernier, A. M., Taylor, R., Terrier, M., Tluczykont, C., Trichard, K., Valeriu, C., van Eldik, G., Vasileiadi, C., Venter, A., Viana, P., Vincent, H. J., Völk, F., Volpe, M., Vorster, S. J., Wagner, P., Wagner, M., Ward, M., Weidinger, Q., Weitzel, R., White, A., Wierzcholska, P., Willmann, A., Wörnlein, D., Wouter, M., Zacharia, A. A., Zdziarski, A., Zech, and H. S., Zechlin

Subjects
catalog, general(HESS J0632+057, VER J0633+057) [gamma rays], Acceleration of particles, binaries:general, Astrophysics, telescope, 01 natural sciences, general [binaries], ls-i +61-degrees-303, emission, i+61 303, 010303 astronomy & astrophysics, HESS - Abteilung Hofmann, acceleration of particle, media_common, acceleration of particles, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), WR star binaries, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Gamma ray, general. [Gamma rays], Orbital period, veritas observations, winds, Orbit, binaries: general, i+61-degrees-303, Astrophysics - High Energy Astrophysical Phenomena, general (HESS J0632+057, VER J0633+057) [gamma rays], [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Hochenergie-Astrophysik Theorie - Abteilung Hofmann, FOS: Physical sciences, Context (language use), Ephemeris, gamma rays: general, 0103 physical sciences, WR star binarie, Cherenkov radiation, 010308 nuclear & particles physics, variability, Institut für Physik und Astronomie, Astronomy and Astrophysics, Light curve, Space and Planetary Science, Sky, ddc:520, general [gamma rays], gamma rays: general(hess j0632+057, ver j0633+057), discovery
Abstract

HESS J0632+057 is the only gamma-ray binary known so far whose position in the sky allows observations with ground-based observatories both in the northern and southern hemispheres. Here we report on long-term observations of HESS J0632+057 conducted with the VERITAS and H.E.S.S. Cherenkov Telescopes and the X-ray Satellite Swift, spanning a time range from 2004 to 2012 and covering most of the system's orbit. The VHE emission is found to be variable, and is correlated with that at X-ray energies. An orbital period of $315 ^{+6}_{-4}$ days is derived from the X-ray data set, which is compatible with previous results, $P = (321 \pm 5$) days. The VHE light curve shows a distinct maximum at orbital phases close to 0.3, or about 100 days after periastron passage, which coincides with the periodic enhancement of the X-ray emission. Furthermore, the analysis of the TeV data shows for the first time a statistically significant ($> 6.5 \sigma$) detection at orbital phases 0.6--0.9. The obtained gamma-ray and X-ray light curves and the correlation of the source emission at these two energy bands are discussed in the context of the recent ephemeris obtained for the system. Our results are compared to those reported for other gamma-ray binaries., Comment: 35 pages, 8 figures, accepted for publication in ApJ

Published
2014
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