Title: | PKS2005-489 at VHE: four years of monitoring with HESS and simultaneous multi-wavelength observations |
Authors: | Acero, F. Aharonian, F. Akhperjanian, A. G. Anton, G. de Almeida UB Bazer-Bachi, A. R. Becherini, Y. Behera, B. Benbow, W. Bernloehr, K. Bochow, A. Katz, U. Ripken, J. Kaufmann, S. Kerschhaggl, M. Khangulyan, D. Dalton, M. Khelifi, B. Keogh, D. Klochkov, D. Kluzniak, W. Superina, G. de Naurois M Pelletier, G. Kneiske, T. Rob, L. Komin, N. Kosack, K. Schwarzburg, S. Kossakowski, R. Lamanna, G. Lenain, J. -. P. Espigat, P. Lohse, T. Marandon, V. Martineau-Huynh, O. Marcowith, A. Bolmont, J. Rosier-Lees, S. Nedbal, D. Schwemmer, S. Masbou, J. Maurin, D. Szostek, A. McComb, T. J. L. Nekrassov, D. Nicholas, B. Niemiec, J. Boisson, C. Nolan, S. J. Ohm, S. Costamante, L. Shalchi, A. Petrucci, P. -. O. Tam, P. H. Olive, J. -. F. Wilhelmi, E. D. O. Orford, K. J. Pita, S. Puehlhofer, G. Punch, M. Coignet, G. Quirrenbach, A. Raubenheimer, B. C. Eger, P. Tavernet, J. -. P. Rowell, G. Raue, M. Rayner, S. M. Renaud, M. Rudak, B. Rulten, C. B. Ruppel, J. Egberts, K. Sahakian, V. Santangelo, A. Moderski, R. Sikora, M. Schlickeiser, R. Brucker, J. Schoeck, F. M. Skilton, J. L. Sol, H. Stawarz, L. Gerbig, D. Steenkamp, R. Brun, F. Terrier, R. Stegmann, C. Daniel, M. K. Stinzing, F. Tibolla, O. Tluczykont, M. van Eldik C Hoffmann, A. Brun, P. Davids, I. D. Vasileiadis, G. Fallon, L. Venter, C. Venter, L. Giebels, B. Vialle, J. P. Vincent, P. Vivier, M. Arribas, M. P. Voelk, H. J. Volpe, F. Wagner, S. J. Ward, M. Degrange, B. Farnier, C. Buehler, R. Glicenstein, J. F. Zdziarski, A. A. Zech, A. Hofmann, W. Collaboration, H. E. S. S. Bulik, T. Buesching, I. Boutelier, T. Chadwick, P. M. Charbonnier, A. Chaves, R. C. G. Mehault, J. Glueck, B. Deil, C. Hofverberg, P. Cheesebrough, A. Chounet, L. -. M. Clapson, A. C. Dickinson, H. J. Djannati-Atai, A. Domainko, W. Medina, M. C. Drury, L. O. Dubois, F. Panter, M. Holleran, M. Fegan, S. Dubus, G. Dyks, J. Dyrda, M. Feinstein, F. Fiasson, A. Foerster, A. Ostrowski, M. Fontaine, G. Fuessling, M. Borrel, V. Goret, P. Gabici, S. Gallant, Y. A. Gerard, L. Goering, D. Hauser, M. Heinz, S. Rieger, F. Heinzelmann, G. Henri, G. Hoppe, S. Hermann, G. Moulin, E. Hinton, J. A. Horns, D. Jacholkowska, A. de Jager OC Schwanke, U. Jahn, C. Naumann-Godo, M. Jung, I. Pedaletti, G. Katarzynski, K. |
First Published: | 9-Mar-2010 |
Publisher: | EDP Sciences for European Southern Observatory (ESO) |
Citation: | Astronomy & Astrophysics, 2010, 511 |
Abstract: | Aims. Our aim is to study the very high energy (VHE; E>100 GeV) γ-ray emission from BL Lac objects and the evolution in time of their broad-band spectral energy distribution (SED).
Methods. VHE observations of the high-frequency peaked BL Lac object PKS 2005-489 were made with the High Energy Stereoscopic System (HESS) from 2004 through 2007. Three simultaneous multi-wavelength campaigns at lower energies were performed during the HESS data taking, consisting of several individual pointings with the XMM-Newton and RXTE satellites.
Results. A strong VHE signal, ~17σ total, from PKS 2005-489 was detected during the four years of HESS observations (90.3 h live time). The integral flux above the average analysis threshold of 400 GeV is ~3% of the flux observed from the Crab Nebula and varies weakly on time scales from days to years. The average VHE spectrum measured from ~300 GeV to ~5 TeV is characterized by a power law with a photon index, . At X-ray energies the flux is observed to vary by more than an order of magnitude between 2004 and 2005. Strong changes in the X-ray spectrum () are also observed, which appear to be mirrored in the VHE band.
Conclusions. The SED of PKS 2005-489, constructed for the first time with contemporaneous data on both humps, shows significant evolution. The large flux variations in the X-ray band, coupled with weak or no variations in the VHE band and a similar spectral behavior, suggest the emergence of a new, separate, harder emission component in September 2005. |
DOI Link: | 10.1051/0004-6361/200913073 |
ISSN: | 0004-6361 |
Links: | http://hdl.handle.net/2381/11163 http://www.aanda.org/articles/aa/abs/2010/03/aa13073-09/aa13073-09.html |
Version: | Publisher Version |
Status: | Peer-reviewed |
Type: | Journal Article |
Rights: | Copyright © 2010 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO. |
Appears in Collections: | Published Articles, Dept. of Physics and Astronomy
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