Spectrum and variability of the Galactic center VHE γ-ray source HESS J1745-290

van Eldik C, Aharonian F, Akhperjanian AG, Anton G, De Almeida UB, Bazer-Bachi AR, Becherini Y, Behera B, Bernloehr K, Boisson C, Bochow A, Borrel V, Braun I, Brion E, Brucker J, Brun P, Buehler R, Bulik T, Buesching I, Boutelier T, Chadwick PM, Charbonnier A, Chaves RCG, Cheesebrough A, Chounet LM, Clapson AC, Coignet G, 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, Emmanoulopoulos D, Espigat P, Farnier C, Feinstein F, Fiasson A, Foerster A, Fontaine G, Fuessling M, Gabici S, Gallant YA, Gerard L, Giebels B, Glicenstein JF, Glueck B, Goret P, Hauser D, Hauser M, Heinz S, Heinzelmann G, Henri G, Hermann G, Hinton JA, Hoffmann A, Hofmann W, Holleran M, Hoppe S, Horns D, Jacholkowska A, De Jager OC, Jung I, Katarzynski K, Katz U, Kaufmann S, Kendziorra E, Kerschhaggl M, Khangulyan D, Khelifi B, Keogh D, Komin N, Kosack K, Lamanna G, Lenain JP, Lohse T, Marandon V, Martin JM, Martineau-Huynh O, Marcowith A, Maurin D, Mccomb TJL, Medina MC, Moderski R, Moulin E, Naumann-Godo M, De Naurois M, Nedbal D, Nekrassov D, Niemiec J, Nolan SJ, Ohm S, Olive JF, Wilhelmi EDO, 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, Renaud M, Rieger F, Ripken J, Rob L, Rolland L, Rosier-Lees S, Rowell G, Rudak B, Rulten CB, Ruppel J, Sahakian V, Santangelo A, Schlickeiser R, Schoeck FM, Schroeder R, Schwanke U, Schwarzburg S, Schwemmer S, Shalchi A, Skilton JL, Sol H, Spangler D, Stawarz L, Steenkamp R, Stegmann C, Superina G, Szostek A, Tam PH, Tavernet JP, Terrier R, Tibolla O, Van Eldik C, Vasileiadis G, Venter C, Venter L, Vialle JP, Vincent P, Vivier M, Voelk HJ, Volpe F, Wagner SJ, Ward M, Zdziarski AA, Zech A (2009)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2009

Journal

Book Volume: 503

Pages Range: 817-825

Journal Issue: 3

DOI: 10.1051/0004-6361/200811569

Abstract

Aims. A detailed study of the spectrum and variability of the source HESS J1745-290 in the Galactic Center (GC) region using new data from the H.E.S.S. array of Cherenkov telescopes is presented. Flaring activity and quasi periodic oscillations (QPO) of HESS J1745-290 are investigated. Methods. The image analysis is performed with a combination of a semi-analytical shower model and the statistical moment-based Hillas technique. The spectrum and lightcurves of HESS J1745-290 are derived with a likelihood method based on a spectral shape hypothesis. Rayleigh tests and Fourier analysis of the H.E.S.S. GC signal are used to study the periodicity of the source. Results. With a three-fold increase in statistics compared to previous work, a deviation from a simple power law spectrum is detected for the first time. The measured energy spectrum over the three years 2004, 2005 and 2006 of data taking is compatible with both a power law spectrum with an exponential cut-off and a broken power law spectrum. The curvature of the energy spectrum is likely to be intrinsic to the photon source, as opposed to effects of interstellar absorption. The power law spectrum with an exponential cut-off is characterized by a photon index of 2.10 ± 0.04 ± 0.10 and a cut-off energy at 15.7 ± 3.4±2.5 TeV. The broken power law spectrum exhibits spectral indices of 2.02 ± 0.08 ± 0.10 and 2.63 ± 0.14 ± 0.10 with a break energy at 2.57 ± 0.19stat ± 0.44 TeV. No significant flux variation is found. Increases in the γ-ray flux of HESS J1745-290 by at least a factor of two would be required for a 3cr detection of a flare with time scales of an hour. Investigation of possible QPO activity at periods claimed to be detected in X-rays does not show any periodicities in the H.E.S.S. signal. © ESO 2009.

Authors with CRIS profile

Involved external institutions

Max-Planck-Institut für Kernphysik (MPIK) / Max Planck Institute for Nuclear Physics Germany (DE) Ruprecht-Karls-Universität Heidelberg Germany (DE) Université Toulouse III - Paul Sabatier France (FR) Centre CEA de Saclay (Essonne) France (FR) Université Joseph Fourier (UJF Grenoble 1) France (FR) Durham University United Kingdom (GB) Noordwes-Universiteit / North-West University South Africa (ZA) École Polytechnique - Université Paris-Saclay France (FR) Jagiellonian University / Uniwersytet Jagielloński (UJ) Poland (PL) University of Montpellier / Université Montpellier France (FR) Nicolaus Copernicus University (NCU) / Uniwersytet Mikołaja Kopernika w Toruniu (UMK) Poland (PL) Eberhard Karls Universität Tübingen Germany (DE) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR) Institute of Nuclear Physics PAN / Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego PAN Poland (PL) Yerevan Physics Institute (YerPhI) / Երևանի Ֆիզիկայի Ինստիտուտ Armenia (AM) Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences Poland (PL) Institut national de physique nucléaire et de physique des particules (IN2P3) France (FR) Humboldt-Universität zu Berlin Germany (DE) Dublin Institute for Advanced Studies (DIAS) Ireland (IE) Universität Hamburg (UHH) Germany (DE) University of Leeds United Kingdom (GB) Univerzita Karlova v Praze / Charles University in Prague Czech Republic (CZ) University of Adelaide Australia (AU) Ruhr-Universität Bochum (RUB) Germany (DE) University of Namibia (UNAM) Namibia (NA)

How to cite

APA:

van Eldik, C., Aharonian, F., Akhperjanian, A.G., Anton, G., De Almeida, U.B., Bazer-Bachi, A.R.,... Zech, A. (2009). Spectrum and variability of the Galactic center VHE γ-ray source HESS J1745-290. Astronomy & Astrophysics, 503(3), 817-825. https://doi.org/10.1051/0004-6361/200811569

MLA:

van Eldik, Christopher, et al. "Spectrum and variability of the Galactic center VHE γ-ray source HESS J1745-290." Astronomy & Astrophysics 503.3 (2009): 817-825.

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