Discovery of TeV gamma-ray emission toward supernova remnant SNR G78.2+2.1

E. Aliu, 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. DukeJ. Dumm, V. V. Dwarkadas, M. Errando, A. Falcone, S. Federici, 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'Faoláin De Bhróithe, R. A. Ong, M. Orr, A. N. Otte, D. Pandel, N. Park, J. S. Perkins, M. Pohl, A. Popkow, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, C. Skole, I. Telezhinsky, G. Tešić, 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

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Abstract

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°.23±0°.03 stat+0°.04-0°.02sys and its spectrum is well-characterized by a differential power law (dN/dE = N0 × (E/TeV)) with a photon index of Γ = 2.37±0.14stat ±0.20sys and a flux normalization of N0 = 1.5±0.2stat±0.4 sys×10-12 photon TeV-1cm -2s-1. This yields an integral flux of 5.2±0.8 stat±1.4sys×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.

Original languageEnglish (US)
Article number93
JournalAstrophysical Journal
Volume770
Issue number2
DOIs
StatePublished - Jun 20 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bird, R., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., ... Zitzer, B. (2013). Discovery of TeV gamma-ray emission toward supernova remnant SNR G78.2+2.1. Astrophysical Journal, 770(2), [93]. https://doi.org/10.1088/0004-637X/770/2/93