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

Research output: Contribution to journalArticle

40 Scopus citations

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

Keywords

  • ISM: supernova remnants
  • acceleration of particles
  • cosmic rays
  • gamma rays: general

Fingerprint Dive into the research topics of 'Discovery of TeV gamma-ray emission toward supernova remnant SNR G78.2+2.1'. Together they form a unique fingerprint.

Cite this