%0 Journal Article
%T Evidence for VHE Gamma-ray Emission from the Distant BL Lac PG 1553+113
%+ Laboratoire Leprince-Ringuet (LLR)
%+ AstroParticule et Cosmologie (APC (UMR_7164))
%+ Laboratoire de Physique Théorique et Astroparticules (LPTA)
%+ Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE)
%A Aharonian, F.
%A Akhperjanian, A.G.
%A Bazer-Bachi, A.R.
%A Beilicke, M.
%A Benbow, Wystan
%A Berge, David
%A Bernlohr, K.
%A Boisson, C.
%A Bolz, O.
%A Borrel, V.
%A Braun, I.
%A Breitling, F.
%A Brown, A.M.
%A Buhler, R.
%A Carrigan, S.
%A Chadwick, P.M.
%A Chounet, L.-M.
%A Cornils, R.
%A Costamante, L.
%A Degrange, B.
%A Dickinson, H.J.
%A Djannati-Ataï, A.
%A Drury, L.O'C.
%A Dubus, G.
%A Egberts, K.
%A Emmanoulopoulos, D.
%A Espigat, P.
%A Feinstein, F.
%A Fontaine, G.
%A Funk, S.
%A Gallant, Y.
%A Giebels, B.
%A Glicenstein, J.F.
%A Goret, P.
%A Hadjichristidis, C.
%A Hauser, D.
%A Hauser, M.
%A Heinzelmann, G.
%A Henri, G.
%A Hermann, G.
%A Hinton, J.A.
%A Hofmann, W.
%A Holleran, M.
%A Horns, Dieter
%A Jacholkowska, A.
%A de Jager, O.C.
%A Khelifi, B.
%A Klages, S.
%A Komin, Nu.
%A Konopelko, A.
%A Latham, I.J.
%A Le Gallou, R.
%A Lemiere, A.
%A Lemoine-Goumard, M.
%A Lohse, T.
%A Martin, J.M.
%A Martineau-Huynh, O.
%A Marcowith, A.
%A Masterson, C.
%A Mccomb, T.J.L.
%A de Naurois, M.
%A Nedbal, D.
%A Nolan, S.J.
%A Noutsos, A.
%A Orford, K.J.
%A Osborne, J.L.
%A Ouchrif, M.
%A Panter, M.
%A Pelletier, G.
%A Pita, S.
%A Puhlhofer, G.
%A Punch, M.
%A Raubenheimer, B.C.
%A Raue, M.
%A Rayner, S.M.
%A Reimer, A.
%A Reimer, O.
%A Ripken, J.
%A Rob, L.
%A Rolland, L.
%A Rowell, G.
%A Sahakian, V.
%A Sauge, L.
%A Schlenker, S.
%A Schlickeiser, R.
%A Schuster, C.
%A Schwanke, U.
%A Siewert, M.
%A Sol, H.
%A Spangler, D.
%A Steenkamp, R.
%A Stegmann, C.
%A Superina, G.
%A Tavernet, J.-P.
%A Terrier, R.
%A Theoret, C.G.
%A Tluczykont, M.
%A van Eldik, C.
%A Vasileiadis, G.
%A Venter, C.
%A Vincent, P.
%A Volk, H.J.
%A Wagner, S.J.
%A Ward, M.
%Z 5 pages, 3 figures; accepted (Jan. 19, 2006) for publication in Astronomy & Astrophysics
%< avec comité de lecture
%Z APC-06-02
%@ 0004-6361
%J Astronomy and Astrophysics - A&A
%I EDP Sciences
%V 448
%P L19-L23
%8 2006
%D 2006
%Z astro-ph/0601545
%R 10.1051/0004-6361:200600010
%K Galaxies: active
%K BL lacertae objects: Individual: PG 1553+113
%K Gamma rays: observations
%Z Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]Journal articles
%X The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. Using the H.E.S.S. standard analysis, an excess was measured at the 4.0 sigma level in these observations (7.6 hours live time). Three alternative, lower-threshold analyses yield >5 sigma excesses. The observed integral flux above 200 GeV is (4.8 +/- 1.3_{stat} +/- 1.0_{syst}) x10^{-12} 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 Gamma=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.
%G English
%Z HESS
%L in2p3-00025548
%U https://hal.in2p3.fr/in2p3-00025548
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