van Eldik C, Abramowski A, Acero F, Aharonian F, Akhperjanian AG, Anton G, De Almeida UB, Bazer-Bachi AR, Becherini Y, Behera B, Benbow W, Bernloehr K, Bochow A, Boisson C, Bolmont J, Borrel V, Brucker J, Brun F, Brun P, Buehler R, Bulik T, Buesching I, Boutelier T, Chadwick PM, Charbonnier A, Chaves RCG, Cheesebrough A, Chounet LM, Clapson AC, Coignet G, Conrad J, Costamante L, Dalton M, Daniel MK, Davids ID, Degrange B, Deil C, Dickinson HJ, Djannati-Atai A, Domainko W, Drury LO, Dubois F, Dubus G, Dyks J, Dyrda M, Egberts K, Eger P, Espigat P, Fallon L, Farnier C, Fegan S, Feinstein F, Fernandes MV, Fiasson A, Foerster A, Fontaine G, Fuessling M, Gabici S, Gallant YA, Gerard L, Gerbig D, Giebels B, Glicenstein JF, Glueck B, Goret P, Göring D, Hampf D, Hauser M, Heinz S, Heinzelmann G, Henri G, Hermann G, Hinton JA, Hoffmann A, Hofmann W, Hofverberg P, Holleran M, Hoppe S, Horns D, Jacholkowska A, De Jager OC, Jahn C, Jung I, Katarzynski K, Katz U, Kaufmann S, Kerschhaggl M, Khangulyan D, Khelifi B, Keogh D, Klochkov D, Kluzniak W, Kneiske T, Komin N, Kosack K, Kossakowski R, Lamanna G, Lenain JP, Lohse T, Lu CC, Marandon V, Marcowith A, Masbou J, Maurin D, Mccomb TJL, Medina MC, Mehault J, Moderski R, Moulin E, Naumann-Godo M, De Naurois M, Nedbal D, Nekrassov D, Nguyen N, Nicholas B, Niemiec J, Nolan SJ, Ohm S, Olive JF, Wilhelmi EDO, Opitz B, Orford KJ, Ostrowski M, Panter M, Arribas MP, Pedaletti G, Pelletier G, Petrucci PO, Pita S, Puehlhofer G, Punch M, Quirrenbach A, Raubenheimer BC, Raue M, Rayner SM, Reimer O, Renaud M, De Los Reyes R, Rieger F, Ripken J, Rob L, Rosier-Lees S, Rowell G, Rudak B, Rulten CB, Ruppel J, Ryde F, Sahakian V, Santangelo A, Schlickeiser R, Schoeck FM, Schoenwald A, Schwanke U, Schwarzburg S, Schwemmer S, Shalchi A, Sushch I, Sikora M, Skilton JL, Sol H, Stawarz L, Steenkamp R, Stegmann C, Stinzing F, Superina G, Szostek A, Tam PH, Tavernet JP, Terrier R, Tibolla O, Tluczykont M, Valerius K, Van Eldik C, Vasileiadis G, Venter C, Venter L, Vialle JP, Viana A, Vincent P, Vivier M, Voelk HJ, Volpe F, Vorobiov S, Wagner SJ, Ward M, Zdziarski AA, Zech A, Zechlin HS (2010)
Publication Language: English
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2010
Publisher: EDP Sciences
Book Volume: 520
Pages Range: A83
Article Number: aa14484-10
Journal Issue: 13
DOI: 10.1051/0004-6361/201014484
Context. Observations of very high-energy γ-rays from blazars provide information about acceleration mechanisms occurring in their innermost regions. Studies of variability in these objects lead to a better understanding of the mechanisms in play. Aims. To investigate the spectral and temporal variability of VHE (>100 GeV) γ-rays of the well-known high-frequency-peaked BL Lac object PKS 2155-304 with the HESS imaging atmospheric Cherenkov telescopes over a wide range of flux states. Methods. Data collected from 2005 to 2007 were analyzed. Spectra were derived on time scales ranging from 3 years to 4 min. Light curve variability was studied through doubling timescales and structure functions and compared with red noise process simulations. Results. The source was found to be in a low state from 2005 to 2007, except for a set of exceptional flares that occurred in July 2006. The quiescent state of the source is characterized by an associated mean flux level of (4.32 ± 0.09 ± 0.86) × 10 cm s above 200 GeV, or approximately 15\% of the Crab Nebula, and a power-law photon index of Γ = 3.53 ± 0.06 ± 0.10. During the flares of July 2006, doubling timescales of ∼2 min are found. The spectral index variation is examined over two orders of magnitude in flux, yielding different behavior at low and high fluxes, which is a new phenomenon in VHE γ-ray emitting blazars. The variability amplitude characterized by the fractional rms F is strongly energy-dependent and is E. The light curve rms correlates with the flux. This is the signature of a multiplicative process that can be accounted for as a red noise with a Fourier index of ∼2. Conclusions. This unique data set shows evidence of a low-level γ-ray emission state from PKS 2155-304 that possibly has a different origin than the outbursts. The discovery of the light curve lognormal behavior might be an indicator of the origin of aperiodic variability in blazars. © ESO, 2010.
APA:
van Eldik, C., Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A.G., Anton, G.,... Zechlin, H.-S. (2010). VHE γ-ray emission of PKS2155-304: Spectral and temporal variability. Astronomy & Astrophysics, 520(13), A83. https://doi.org/10.1051/0004-6361/201014484
MLA:
van Eldik, Christopher, et al. "VHE γ-ray emission of PKS2155-304: Spectral and temporal variability." Astronomy & Astrophysics 520.13 (2010): A83.
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