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          Institute: MPI für Kernphysik     Collection: High-Energy Astrophysics     Display Documents

ID: 28875.0, MPI für Kernphysik / High-Energy Astrophysics
An unidentified TeV source in the vicinity of Cygnus OB2
Authors:Aharonian, F.; Akhperjanian, A.; Beilicke, M.; Bernlöhr, K.; Borst, H.; Bojahr, H.; Bolz, O.; Coarasa, T.; Contreras, J.; Cortina, J.; Denninghoff, S.; Fonseca, V.; Girma, M.; Gotting, N.; Heinzelmann, G.; Hermann, G.; Heusler, A.; Hofmann, W.; Horns, D.; Jung, I.; Kankanyan, R.; Kestel, M.; Kettler, J.; Kohnle, A.; Konopelko, A.; Kornmeyer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Magnussen, N.; Mang, O.; Meyer, H.; Milite, M.; Mirzoyan, R.; Moralejo, A.; Ona, E.; Panter, M.; Plyasheshnikov, A.; Prahl, J.; Pühlhofer, G.; Rauterberg, G.; Reyes, R.; Rhode, W.; Ripken, J.; Rohring, A.; Rowell, G. P.; Sahakian, V.; Samorski, M.; Schilling, M.; Schroder, F.; Siems, M.; Sobzynska, D.; Stamm, W.; Tluczykont, M.; Völk, H. J.; Wiedner, C. A.; Wittek, W.; Uchiyama, Y.; Takahashi, T.
Date of Publication (YYYY-MM-DD):2002-10
Title of Journal:Astronomy & Astrophysics
Journal Abbrev.:Astron. Astrophys.
Issue / Number:2
Start Page:L37
End Page:L40
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Deep observation (similar to113 hrs) of the Cygnus region at TeV energies using the HEGRA stereoscopic system of air Cerenkov telescopes has serendipitously revealed a signal positionally inside the core of the OB association Cygnus OB2, at the edge of the 95% error circle of the EGRET source 3EG J2033+4118, and similar to0.5degrees north of Cyg X-3. The source centre of gravity is RA alpha(J2000): 20(hr)32(m)07(s) +/- 9.2(stat)(s) +/- 2.2(sys)(s), Dec delta(J2000): +41degrees30'30" +/- 2.0(stat)' +/- 0.4(sys)'. The source is steady, has a post-trial significance of +4.6sigma, indication for extension with radius 5.6' at the similar to3sigma level, and has a differential power-law flux with hard photon index of -1.9 +/- 0.3(stat) +/- 0.3(sys). The integral flux above 1 TeV amounts similar to3% that of the Crab. No counterpart for the TeV source at other wavelengths is presently identified, and its extension would disfavour an exclusive pulsar or AGN origin. If associated with Cygnus OB2, this dense concentration of young, massive stars provides an environment conducive to multi-TeV particle acceleration and likely subsequent interaction with a nearby gas cloud. Alternatively, one could envisage gamma-ray production via a jet-driven termination shock.
Free Keywords:gamma rays : observations; stars : early-type; Galaxy : open clusters and associations : individual : Cygnus OB2
External Publication Status:published
Document Type:Article
Affiliations:MPI für Kernphysik/Group H. J. Völk/High Energy Astrophysics (F. Aharonian)
MPI für Kernphysik/Group W. Hofmann/Experimental High-Energy Astrophysics (M. Panter, G. Hermann)
External Affiliations:Max Planck Inst Phys & Astrophys, D-80805 Munich, Germany; Univ Complutense, Fac Ciencias Fis, E-28040 Madrid, Spain; Univ Hamburg, Inst Expt Phys, D-22761 Hamburg, Germany; Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany; Berg Univ Gesamthsch Wuppertal, Fachbereich Phys, D-42097 Wuppertal, Germany; Yerevan Phys Inst, Yerevan 375036, Armenia; Inst Space & Astronaut Sci, Kanagawa 2298510, Japan
Identifiers:ISI:000178247400003 [ID No:1]
ISSN:0004-6361 [ID No:2]
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