Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/11152
Title: Discovery of VHE gamma rays from PKS 2005-489
Authors: Aharonian, F.
Akhperjanian, A. G.
Aye, K. M.
Bazer-Bachi, A. R.
Beilicke, M. B.
Benbow, W.
Berge, D.
Berghaus, P.
Bernlohr, K.
Boisson, C.
Bolz, O.
Braun, I.
Breitling, F.
Brown, A. M.
Gordo, J. B.
Chadwick, P. M.
Chounet, L. M.
Cornils, R.
Costamante, L.
Degrange, B.
Djannati-Atai, A.
Drury, L. O. C.
Dubus, G.
Emmanoulopoulos, D.
Espigat, P.
Feinstein, F.
Fleury, P.
Fontaine, G.
Fuchs, Y.
Funk, S.
Gallant, Y. A.
Giebels, B.
Gillessen, S.
Glicenstein, J. F.
Goret, P.
Hadjichristidis, C.
Hauser, M.
Heinzelmann, G.
Henri, G.
Hermann, G.
Hinton, J. A.
Hofmann, W.
Holleran, M.
Horns, D.
de Jager O. C.
Khelifi, B.
Komin, N.
Konopelko, A.
Latham, I. J.
Le Gallou R.
Lemiere, A.
Lemoine-Goumard, M.
Leroy, N.
Lohse, T.
Martineau-Huynh, O.
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.
Puhlhofer, G.
Punch, M.
Raubenheimer, B. C.
Raue, M.
Raux, J.
Rayner, S. M.
Redondo, I.
Reimer, A.
Reimer, O.
Ripken, J.
Rob, L.
Rolland, L.
Rowell, G.
Sahakian, V.
Sauge, L.
Schlenker, S.
Schlickeiser, R.
Schuster, C.
Schwanke, U.
Siewert, M.
Sol, H.
Steenkamp, R.
Stegmann, C.
Tavernet, J. P.
Terrier, R.
Theoret, C. G.
Tluczykont, M.
Vasileiadis, G.
Venter, C.
Vincent, P.
Volk, H. J.
Wagner, S. J.
First Published: Jun-2005
Publisher: EDP Sciences for European Southern Observatory (ESO)
Citation: Astronomy & Astrophysics, 2005, 436 (2), pp. L17-L20
Abstract: The high-frequency peaked BL Lac PKS 2005-489 (z=0.071) was observed in 2003 and 2004 with the HESS stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. A signal was detected at the 6.7$\sigma$ level in the 2004 observations (24.2 h live time), but not in the 2003 data set (27.3 h live time). PKS 2005-489 is the first blazar independently discovered by HESS to be an emitter of VHE photons, and only the second such blazar in the Southern Hemisphere. The integral flux above 200 GeV observed in 2004 is ( $6.9\pm1.0_{\rm stat}\pm1.4_{\rm syst}) \times 10^{-12}$ cm-2 s-1, corresponding to ~2.5% of the flux observed from the Crab Nebula. The 99% upper limit on the flux in 2003, I(>200 GeV $) < 5.2 \times 10^{-12}$ cm-2 s-1, is smaller than the flux measured in 2004, suggesting an increased level of activity in 2004. However, the data show no evidence for significant variability on any time scale less than a year. An energy spectrum is measured and is characterized by a very soft power law (photon index of $\Gamma=4.0\pm0.4$).
DOI Link: 10.1051/0004-6361:200500113
ISSN: 0004-6361
Links: http://hdl.handle.net/2381/11152
http://www.aanda.org/articles/aa/abs/2005/23/aahc292/aahc292.html
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2005 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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