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Discovery of TeV Gamma-Ray emission toward supernova remnant SNR G78.2+2.1

  • We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr 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 degrees.23 +/- 0 degrees.03(stat-0 degrees.02sys)(+0 degrees.04) and its spectrum is well-characterized by a differential power law (dN/dE = N-0 x (E/TeV)-Gamma) with a photon index of Gamma = 2.37 +/- 0.14(stat) +/- 0.20(sys) and a flux normalization of N-0 = 1.5 +/- 0.2(stat) +/- 0.4(sys) x 10(-12) photon TeV-1 cm(-2) s(-1). This yields an integral flux of 5.2 +/- 0.8(stat) +/- 1.4(sys) xWe report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr 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 degrees.23 +/- 0 degrees.03(stat-0 degrees.02sys)(+0 degrees.04) and its spectrum is well-characterized by a differential power law (dN/dE = N-0 x (E/TeV)-Gamma) with a photon index of Gamma = 2.37 +/- 0.14(stat) +/- 0.20(sys) and a flux normalization of N-0 = 1.5 +/- 0.2(stat) +/- 0.4(sys) x 10(-12) photon TeV-1 cm(-2) s(-1). This yields an integral flux of 5.2 +/- 0.8(stat) +/- 1.4(sys) x 10(-12) photon 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 SNR shock.show moreshow less

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Author:E. tAliu, S. Archambault, T. Arlen, T. Aune, M. Beilicke, W. Benbow, R. Bird, A. Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, C. Duke, J. Dumm, V. V. Dwarkadas, M. Errando, A. Falcone, Simone FedericiGND, Q. Feng, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, G. H. Gillanders, S. Godambe, E. V. Gotthelf, S. Griffin, J. Grube, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, T. B. Humensky, P. Kaaret, N. Karlsson, M. Kertzman, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, K. Lee, A. S. Madhavan, G. Maier, P. Majumdar, S. McArthur, A. McCann, J. Millis, P. Moriarty, R. Mukherjee, T. Nelson, A. O'Faolain de Bhroithe, R. A. Ong, M. Orr, A. N. Otte, D. Pandel, N. Park, J. S. Perkins, Martin PohlORCiDGND, A. Popkow, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, Jens Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Sentuerk, C. Skole, Igor Telezhinsky, G. Tesic, M. Theiling, S. Thibadeau, K. Tsurusaki, J. Tyler, A. Varlotta, V. V. Vassiliev, S. Vincent, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, R. Welsing, D. A. Williams, B. Zitzer
DOI:https://doi.org/10.1088/0004-637X/770/2/93
ISSN:0004-637X (print)
Parent Title (English):The astrophysical journal : an international review of spectroscopy and astronomical physics
Publisher:IOP Publ. Ltd.
Place of publication:Bristol
Document Type:Article
Language:English
Year of first Publication:2013
Year of Completion:2013
Release Date:2017/03/26
Tag:ISM: supernova remnants; acceleration of particles; cosmic rays; gamma rays: general
Volume:770
Issue:2
Pagenumber:7
Funder:U.S. Department of Energy Office of Science; U.S. National Science Foundation; Smithsonian Institution; NSERC in Canada; Science Foundation Ireland [SFI 10/RFP/AST2748]; Science and Technology Facilities Council in the UK; NASA [NNX11A086G]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert