DISCOVERY OF TeV GAMMA-RAY EMISSION TOWARD SUPERNOVA REMNANT SNR G78.2+2.1

Journal Article · Thu Jun 20 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/770/2/93· OSTI ID:22127096

Aliu, E. ^[1]; Archambault, S. ^[2]; Arlen, T.; Aune, T. ^[3]; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R. ^[4]; Benbow, W. ^[5]; Bird, R.; Cannon, A.; Collins-Hughes, E. ^[6]; Bouvier, A. ^[7]; Bradbury, S. M. ^[8]; Byrum, K. ^[9]; Cesarini, A.; Connolly, M. P. ^[10]; Ciupik, L. ^[11]; Cui, W. ^[12]; others, and

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1. Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)
2. Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada)
3. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
4. Department of Physics, Washington University, St. Louis, MO 63130 (United States)
5. Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)
6. School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
7. Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
8. School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT (United Kingdom)
9. Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)
10. School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)
11. Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)
12. Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)

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 Degree-Sign .23 {+-} 0. Degree-Sign 03{sub stat-0 Degree-Sign .02sys}{sup +0 Degree-Sign .04} and its spectrum is well-characterized by a differential power law (dN/dE = N{sub 0} Multiplication-Sign (E/TeV){sup -{Gamma}}) with a photon index of {Gamma} = 2.37 {+-} 0.14{sub stat} {+-} 0.20{sub sys} and a flux normalization of N{sub 0} = 1.5 {+-} 0.2{sub stat} {+-} 0.4{sub sys} Multiplication-Sign 10{sup -12} photon TeV{sup -1} cm{sup -2} s{sup -1}. This yields an integral flux of 5.2 {+-} 0.8{sub stat} {+-} 1.4{sub sys} Multiplication-Sign 10{sup -12} photon cm{sup -2} s{sup -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.

• OSTI ID: 22127096
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 770; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COSMIC RADIATION
CRAB NEBULA
GAMMA RADIATION
GEV RANGE
HADRONS
PARTICLES
PHOTONS
SPECTRA
TEV RANGE
X RADIATION