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

ID: 276605.0, MPI für Kernphysik / High-Energy Astrophysics
Evidence for VHE gamma-ray emission from the distant BL Lac PG 1553+113
Authors:Aharonian, F.; Akhperjanian, A. G.; Bazer-Bachi, A. R.; Beilicke, M.; Benbow, W.; Berge, D.; Borrel, V.; Bernlöhr, K.; Bolz, O.; Boisson, C:; Glicenstein, J.F.; Breitling, F.; Brown, A. M.; Dickinson, H.J.; Chadwick, P. M.; Braun, I.; Chounet, L.-M.; Cornils, R.; Costamante, L.; Degrange, B.; Djannati-Atai, A.; Drury, L.O'C.; Emmanoulopoulos, D.; Espigat, P.; Feinstein, F.; Jacholkowska, A.; Fontaine, G.; Funk, S.; Gallant, Y. A.; Giebels, B.; Gillessen, S.; Goret, P.; Dubus, G.; Hadjichristidis, C.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Holleran, M.; Horns, D.; de Jager, O. C.; Khélifi, B.; Komin, N.; Konopelko, A.; Latham, I. J.; Le Gallou, R.; Lemoine-Goumard, M.; Lemière, A.; Leroy, N.; Lohse, T.; Marcowith, A.; Masterson, C.; McComb, T. J. L.; de Naurois, M.; Nolan, S. J.; Noutsos, A.; Orford, K. J.; Osborne, J. L.; Ouchrif, M.; Panter, M.; Pelletier, G.; Pita, S.; Fuchs, Y.; Pühlhofer, G.; Punch, M.; Raubenheimer, B. C.; Raue, M.; Raux, J.; Rayner, S. M.; Martin, J.M.; Reimer, A.; Reimer, O.; Ripken, J.; Terrier, R.; Rob, L.; Rolland, L.; Rowell, G.; Sahakian, V.; Saugé, L.; Schlenker, S.; Schlickeiser, R.; Schuster, C.; Schwanke, U.; Siewert, M.; Sol, H.; Steenkamp, R.; Stegmann, C.; Tavernet, J.-P-; Théoret, C. G.; Tluczykont, M.; Venter, C.; Vasileiadis, G.; Vincent, P.; Völk, H. J.; Wagner, S. J.; Martineau-Huynh, O.; Spangler, D.
Research Context:H.E.S.S., galaxies: active -- BL Lacertae objects: individual: PG 1553+113 -- gamma rays: observations
Date of Publication (YYYY-MM-DD):2006-01-19
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:A&A
Issue / Number:2
Start Page:L19
End Page:L23
Copyright:© ESO 2006
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the HESS stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. Using the HESS standard analysis, an excess was measured at the 4.0 level in these observations (7.6 hours live time). Three alternative, lower-threshold analyses yield >5 excesses. The observed integral flux above 200 GeV is (4.8±1.3stat±1.0syst x 1012 cm-2 s-1, and shows no evidence for variability. The measured energy spectrum is characterized by a very soft power law (photon index of Γ = 4.0±0.6). Although the redshift of PG 1553+113 is unknown, there are strong indications that it is greater than z=0.25 and possibly larger than z=0.78. The observed spectrum is interpreted in the context of VHE gamma-ray absorption by the Extragalactic Background Light, and is used to place an upper limit on the redshift of z<0.74.
Free Keywords:galaxies: active -- BL Lacertae objects: individual: PG 1553+113 -- gamma rays: observations
External Publication Status:published
Document Type:Article
Affiliations:MPI für Kernphysik/Group of W. Hofmann/High Energy Astrophysics (F. Aharonian)
MPI für Kernphysik/Group of W. Hofmann/Experimental High-Energy Astrophysics (M. Panter, G. Hermann)
External Affiliations:Yerevan Physics Institute, 2 Alikhanian Brothers Street, 375036 Yerevan, Armenia.
Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK.
Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, 9 av. du Colonel Roche, BP 4346, F-31029 Toulouse Cedex 4, France.
Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
APC, UMR 7164 du CNRS, 11 Place Marcelin Berthelot, F-75231 Paris Cedex 05, France.
Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany.
Laboratoire Univers et Théories (LUTH), UMR 8102 du CNRS, Observatoire de Paris, Section de Meudon, F-92195 Meudon Cedex, France.
Laboratoire de Physique Théorique et Astroparticules, IN2P3/CNRS, Université Montpellier II, CC 70, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France.
Laboratoire Leprince-Ringuet, IN2P3/CNRS, Ecole Polytechnique, F-91128 Palaiseau, France.
Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland.
Landessternwarte, Königstuhl, D-69117 Heidelberg, Germany.
Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Université Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9, France.
DAPNIA/DSM/CEA, CE Saclay, F-91191 Gif-sur-Yvette, France.
Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa.
Laboratoire de Physique Nucléaire et de Hautes Energies, IN2P3/CNRS, Universités Paris VI & VII, 4 Place Jussieu, F-75252 Paris Cedex 05, France.
Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
Institute of Particle and Nuclear Physics (IPNP), Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic.
University of Namibia, Private Bag 13301, Windhoek, Namibia.
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