Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017

F. Aharonian A.G. Akhperjanian A.R. Bazer-Bachi 1 B. Behera M. Beilicke W. Benbow D. Berge K. Bernlöhr C. Boisson 2 O. Bolz V. Borrel 1 I. Braun E. Brion 3 A.M. Brown R. Bühler T. Bulik I. Büsching T. Boutelier 4 S. Carrigan P.M. Chadwic L.-M. Chounet 5 A.C. Clapson G. Coignet 6 R. Cornils L. Costamante B. Degrange 5 H.J. Dickinson A. Djannati-Ataï 7 W. Domainko L.O'C. Drury G. Dubus 5 J. Dyks K. Egberts D. Emmanoulopoulos P. Espigat 8 C. Farnier 9 F. Feinstein 9 A. Fiasson 9 A. F¨orster G. Fontaine 5 Y. Fukui Seb. Funk S. Funk M. Füßling Y.A. Gallant 9 B. Giebels 5 J.F. Glicenstein 3 B. Glück P. Goret 3 C. Hadjichristidis D. Hauser M. Hauser G. Heinzelmann G. Henri 4 G. Hermann J.A. Hinton A. Hoffmann W. Hofmann M. Holleran S. Hoppe D. Horns A. Jacholkowska 9 O.C. De Jager E. Kendziorra M. Kerschhagg B. Khélifi 5 Nu. Komin 9 K. Kosack G. Lamanna 6 I.J. Latham R. Le Gallou A. Lemière 8 M. Lemoine-Goumard 5 J.-P. Lenain 2 T. Lohse J.M. Martin 2 O. Martineau-Huynh 10 A. Marcowith 9 C. Masterson G. Maurin 8 T.J.L. Mccomb R. Moderski Y. Moriguchi E. Moulin 9 M. De Naurois 10 D. Nedbal S.J. Nolan J.-P. Olive 1 K.J. Orford J.L. Osborne M. Ostrowski M. Panter G. Pedaletti G. Pelletier 4 P.-O. Petrucci 4 S. Pita 8 G. P¨uhlhofer M. Punch 8 S. Ranchon 6 B.C. Raubenheimer M. Raue S.M. Rayner O. Reimer M. Renaud J. Ripken L. Rob L. Rolland 3 S. Rosier-Lees 6 G. Rowell B. Rudak J. Ruppel V. Sahakian A. Santangelo L. Saugé S. Schlenker R. Schlickeiser R. Schroder U. Schwanke S. Schwarzburg S. Schwemmer A. Shalchi H. Sol 2 D. Spangler Ł. Stawarz R. Steenkamp C. Stegmann G. Superina 5 T. Takeuchi P.H. Tam J.-P. Tavernet 10 R. Terrier 8 C. Van Eldik G. Vasileiadis 9 C. Venter J.P. Vialle 6 P. Vincent 10 M. Vivier 3 H.J. Volk F. Volpe 5 S.J. Wagner M. Ward
Abstract : Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed emission and its production mechanism using the High Energy Stereoscopic System (H.E.S.S.) experiment. Methods: We report recent observations of the BL Lac source RGB J0152+017 made in late October and November 2007 with the H.E.S.S. array consisting of four imaging atmospheric Cherenkov telescopes. Contemporaneous observations were made in X-rays by the Swift and RXTE satellites, in the optical band with the ATOM telescope, and in the radio band with the Nancay Radio Telescope. Results: A signal of 173 gamma-ray photons corresponding to a statistical significance of 6.6 sigma was found in the data. The energy spectrum of the source can be described by a powerlaw with a spectral index of 2.95+/-0.36stat+/-0.20syst. The integral flux above 300 GeV corresponds to ~2% of the flux of the Crab nebula. The source spectral energy distribution (SED) can be described using a two-component non-thermal synchrotron self-Compton (SSC) leptonic model, except in the optical band, which is dominated by a thermal host galaxy component. The parameters that are found are very close to those found in similar SSC studies in TeV blazars. Conclusions: RGB J0152+017 is discovered as a source of VHE gamma-rays by H.E.S.S. The location of its synchrotron peak, as derived from the SED in Swift data, allows clearly classification it as a high-frequency-peaked BL Lac (HBL).


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Submitted on : Tuesday, June 3, 2008 - 2:00:18 PM
Last modification on : Tuesday, June 3, 2008 - 2:00:18 PM

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F. Aharonian, A.G. Akhperjanian, A.R. Bazer-Bachi, B. Behera, M. Beilicke, et al.. Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017. Astronomy and Astrophysics, EDP Sciences, 2008, 481, pp.L103-L107. <10.1051/0004-6361:200809603>. <in2p3-00263434>

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