Discovery of TeV Gamma-ray Emission Toward Supernova Remnant SNR G78.2+2.1
Creators: name: Aliu, E.
name: Archambault, S.
name: Arlen, T.
name: Aune, T.
name: Beilicke, M.
name: Benbow, W.
name: Bird, R.
name: Bouvier, A.
name: Bradbury, S. M.
name: Buckley, J. H.
name: Bugaev, V.
name: Byrum, K.
name: Cannon, A.
name: Cesarini, A.
name: Ciupik, L.
name: Collins-Hughes, E.
name: Connolly, M. P.
name: Cui, W.
name: Dickherber, R.
name: Duke, C.
name: Dumm, J.
name: Dwarkadas, V. V.
name: Errando, M.
name: Falcone, A.
name: Federici, S.
name: Feng, Q.
name: Finley, J. P.
name: Finnegan, G.
name: Fortson, L.
name: Furniss, A.
name: Galante, N.
name: Gall, D.
name: Gillanders, G. H.
name: Godambe, S.
name: Gotthelf, E. V.
name: Griffin, S.
name: Grube, J.
name: Gyuk, G.
name: Hanna, D.
name: Holder, J.
name: Huan, H.
name: Hughes, G.
name: Humensky, T. B.
name: Kaaret, P.
name: Karlsson, N.
name: Kertzman, M.
name: Khassen, Y.
name: Kieda, D.
name: Krawczynski, H.
name: Krennrich, F.
name: Lang, M. J.
name: Lee, K.
name: Madhavan, A. S
name: Maier, G.
name: Majumdar, P.
name: McArthur, S.
name: McCann, A.
name: Millis, J.
name: Moriarty, P.
name: Mukherjee, R.
name: Nelson, T.
name: de Bhróithe, A. O'Faoláin
name: Ong, R. A.
name: Orr, M.
name: Otte, A. N.
name: Pandel, D.
name: Park, N.
name: Perkins, J. S.
name: Pohl, M.
name: Popkow, A.
name: Prokoph, H.
name: Quinn, J.
name: Ragan, K.
name: Reyes, L. C.
name: Reynolds, P. T.
name: Roache, E.
name: Rose, H. J.
name: Ruppel, J.
name: Saxon, D. B.
name: Schroedter, M.
name: Sembroski, G. H.
name: Şentürk, G. D.
name: Skole, C.
name: Telezhinsky, I.
name: Tešić, G.
name: Theiling, M.
name: Thibadeau, S.
name: Tsurusaki, K.
name: Tyler, J.
name: Varlotta, A.
name: Vassiliev, V. V.
name: Vincent, S.
name: Wakely, S. P.
name: Ward, J. E.
name: Weekes, T. C.
name: Weinstein, A.
name: Weisgarber, T.
name: Welsing, R.
name: Williams, D. A.
name: Zitzer, B.
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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)^{-Γ}) with a photon index of Γ = 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.
description: 18 pages, 5 figures, accepted for publication in ApJ