A&A 508, 561-564 (2009)
DOI: 10.1051/0004-6361/200913323

Probing the ATIC peak in the cosmic-ray electron spectrum with H.E.S.S.

F. Aharonian^{1, 2}, A. G. Akhperjanian³, G. Anton⁴, U. Barres de Almeida⁵, A. R. Bazer-Bachi⁶, Y. Becherini⁷, B. Behera⁸, K. Bernlöhr^{1, 9}, A. Bochow¹, C. Boisson¹⁰, J. Bolmont¹¹, V. Borrel⁶, J. Brucker⁴, F. Brun¹¹, P. Brun¹², R. Bühler¹, T. Bulik¹³, I. Büsching¹⁴, T. Boutelier¹⁵, P. M. Chadwick⁵, A. Charbonnier¹¹, R. C. G. Chaves¹, A. Cheesebrough⁵, L.-M. Chounet¹⁶, A. C. Clapson¹, G. Coignet¹⁷, M. Dalton⁹, M. K. Daniel⁵, I. D. Davids^{18, 14}, B. Degrange¹⁶, C. Deil¹, H. J. Dickinson⁵, A. Djannati-Ataï⁷, W. Domainko¹, L. O'C. Drury², F. Dubois¹⁷, G. Dubus¹⁵, J. Dyks¹³, M. Dyrda¹⁹, K. Egberts¹, D. Emmanoulopoulos⁸, P. Espigat⁷, C. Farnier²⁰, F. Feinstein²⁰, A. Fiasson¹⁷, A. Förster¹, G. Fontaine¹⁶, M. Füßling⁹, S. Gabici², Y. A. Gallant²⁰, L. Gérard⁷, D. Gerbig²¹, B. Giebels¹⁶, J. F. Glicenstein¹², B. Glück⁴, P. Goret¹², D. Göring⁴, D. Hauser⁸, M. Hauser⁸, S. Heinz⁴, G. Heinzelmann²², G. Henri¹⁵, G. Hermann¹, J. A. Hinton²³, A. Hoffmann²⁴, W. Hofmann¹, M. Holleran¹⁴, S. Hoppe¹, D. Horns²², A. Jacholkowska¹¹, O. C. de Jager¹⁴, C. Jahn⁴, I. Jung⁴, K. Katarzyński²⁵, U. Katz⁴, S. Kaufmann⁸, E. Kendziorra²⁴, M. Kerschhaggl⁹, D. Khangulyan¹, B. Khélifi¹⁶, D. Keogh⁵, W. Kluźniak¹³, T. Kneiske²², Nu. Komin²⁰, K. Kosack¹, R. Kossakowski¹⁷, G. Lamanna¹⁷, J.-P. Lenain¹⁰, T. Lohse⁹, V. Marandon⁷, J. M. Martin¹⁰, O. Martineau-Huynh¹¹, A. Marcowith²⁰, J. Masbou¹⁷, D. Maurin¹¹, T. J. L. McComb⁵, M. C. Medina¹⁰, R. Moderski¹³, E. Moulin¹², M. Naumann-Godo¹⁶, M. de Naurois¹¹, D. Nedbal²⁶, D. Nekrassov¹, B. Nicholas²⁷, J. Niemiec¹⁹, S. J. Nolan⁵, S. Ohm¹, J.-F. Olive⁶, E. de Oña Wilhelmi^{1, 7, 28}, K. J. Orford⁵, M. Ostrowski²⁹, M. Panter¹, M. Paz Arribas⁹, G. Pedaletti⁸, G. Pelletier¹⁵, P.-O. Petrucci¹⁵, S. Pita⁷, G. Pühlhofer⁸, M. Punch⁷, A. Quirrenbach⁸, B. C. Raubenheimer¹⁴, M. Raue^{1, 28}, S. M. Rayner⁵, O. Reimer³⁰, M. Renaud¹, F. Rieger^{1, 28}, J. Ripken²², L. Rob²⁶, S. Rosier-Lees¹⁷, G. Rowell²⁷, B. Rudak¹³, C. B. Rulten⁵, J. Ruppel²¹, V. Sahakian³, A. Santangelo²⁴, R. Schlickeiser²¹, F. M. Schöck⁴, R. Schröder²¹, U. Schwanke⁹, S. Schwarzburg²⁴, S. Schwemmer⁸, A. Shalchi²¹, M. Sikora¹³, J. L. Skilton²³, H. Sol¹⁰, D. Spangler⁵, Ł. Stawarz²⁹, R. Steenkamp¹⁸, C. Stegmann⁴, F. Stinzing⁴, G. Superina¹⁶, A. Szostek^{29, 15}, P. H. Tam⁸, J.-P. Tavernet¹¹, R. Terrier⁷, O. Tibolla¹, M. Tluczykont²², C. van Eldik¹, G. Vasileiadis²⁰, C. Venter¹⁴, L. Venter¹⁰, J. P. Vialle¹⁷, P. Vincent¹¹, M. Vivier¹², H. J. Völk¹, F. Volpe¹, S. J. Wagner⁸, M. Ward⁵, A. A. Zdziarski¹³, and A. Zech<sup>10

1</sup>  Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
    e-mail: kathrin.Egberts@uibk.ac.at
²  Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
³  Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
⁴  Universität Erlangen-Nürnberg, Physikalisches Institut, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
⁵  University of Durham, Department of Physics, South Road, Durham DH1 3LE, UK
⁶  Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, 9 Av. du Colonel Roche, BP 4346, 31029 Toulouse Cedex 4, France
⁷  Astroparticule et Cosmologie (APC), CNRS, Université Paris 7 Denis Diderot, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France, UMR 7164 (CNRS, Université Paris VII, CEA, Observatoire de Paris)
⁸  Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
⁹  Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
¹⁰  LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
¹¹  LPNHE, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, CNRS/IN2P3, 4 place Jussieu, 75252 Paris Cedex 5, France
¹²  IRFU/DSM/CEA, CE Saclay, 91191 Gif-sur-Yvette, Cedex, France
¹³  Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland
¹⁴  Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa
¹⁵  Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
¹⁶  Laboratoire Leprince-Ringuet, École Polytechnique, CNRS/IN2P3, 91128 Palaiseau, France
¹⁷  Laboratoire d'Annecy-le-Vieux de Physique des Particules, Université de Savoie, CNRS/IN2P3, 9 chemin de Bellevue, BP 110, 74941 Annecy-le-Vieux Cedex, France
¹⁸  University of Namibia, Private Bag 13301, Windhoek, Namibia
¹⁹  Instytut Fizyki Jądrowej PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland
²⁰  Laboratoire de Physique Théorique et Astroparticules, Université Montpellier 2, CNRS/IN2P3, CC 70, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
²¹  Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
²²  Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
²³  School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, UK
²⁴  Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
²⁵  Toruń Centre for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87-100 Toruń, Poland
²⁶  Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
²⁷  School of Chemistry & Physics, University of Adelaide, Adelaide 5005, Australia
²⁸  European Associated Laboratory for Gamma-Ray Astronomy, jointly supported by CNRS and MPG
²⁹  Obserwatorium Astronomiczne, Uniwersytet Jagielloński, Kraków, Poland
³⁰  Stanford University, HEPL & KIPAC, Stanford, CA 94305-4085, USA

Received 19 September 2009 / Accepted 18 October 2009

Abstract
The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by the ATIC experiment has – together with the PAMELA detection of a rise in the positron fraction up to 100 GeV – motivated many interpretations in terms of dark matter scenarios; alternative explanations assume a nearby electron source like a pulsar or supernova remnant. Here we present a measurement of the cosmic-ray electron spectrum with H.E.S.S. starting at 340 GeV. While the overall electron flux measured by H.E.S.S. is consistent with the ATIC data within statistical and systematic errors, the H.E.S.S. data exclude a pronounced peak in the electron spectrum as suggested for interpretation by ATIC. The H.E.S.S. data follow a power-law spectrum with spectral index of 3.00.1(stat.) 0.3(syst.), which steepens at about 1 TeV.

Key words: cosmic rays -- methods: data analysis

© ESO 2009

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