A&A 483, 509-517 (2008)
DOI: 10.1051/0004-6361:20079230

Exploring a SNR/molecular cloud association within HESS J1745-303

F. Aharonian^{1, 2}, A. G. Akhperjanian³, U. Barres de Almeida⁴, A. R. Bazer-Bachi⁵, B. Behera⁶, M. Beilicke⁷, W. Benbow¹, K. Bernlöhr^{1, 8}, C. Boisson⁹, O. Bolz¹, V. Borrel⁵, I. Braun¹, E. Brion¹⁰, A. M. Brown⁴, R. Bühler¹, T. Bulik¹¹, I. Büsching¹², T. Boutelier¹³, S. Carrigan¹, P. M. Chadwick⁴, L.-M. Chounet¹⁴, A. C. Clapson¹, G. Coignet¹⁵, R. Cornils⁷, L. Costamante^{1, 16}, M. Dalton⁸, B. Degrange¹⁴, H. J. Dickinson⁴, A. Djannati-Ataï¹⁷, W. Domainko¹, L. O'C. Drury², F. Dubois¹⁵, G. Dubus¹³, J. Dyks¹¹, K. Egberts¹, D. Emmanoulopoulos⁶, P. Espigat¹⁷, C. Farnier¹⁸, F. Feinstein¹⁸, A. Fiasson¹⁸, A. Förster¹, G. Fontaine¹⁴, S. Funk¹⁹, M. Füßling⁸, Y. A. Gallant¹⁸, B. Giebels¹⁴, J. F. Glicenstein¹⁰, B. Glück²⁰, P. Goret¹⁰, C. Hadjichristidis⁴, D. Hauser¹, M. Hauser⁶, G. Heinzelmann⁷, G. Henri¹³, G. Hermann¹, J. A. Hinton²¹, A. Hoffmann²², W. Hofmann¹, M. Holleran¹², S. Hoppe¹, D. Horns²², A. Jacholkowska¹⁸, O. C. de Jager¹², I. Jung²⁰, K. Katarzynski²³, E. Kendziorra²², M. Kerschhaggl⁸, B. Khélifi¹⁴, D. Keogh⁴, Nu. Komin¹⁸, K. Kosack¹, G. Lamanna¹⁵, I. J. Latham⁴, M. Lemoine-Goumard¹⁴, J.-P. Lenain⁹, T. Lohse⁸, J. M. Martin⁹, O. Martineau-Huynh²⁴, A. Marcowith¹⁸, C. Masterson², D. Maurin²⁴, T. J. L. McComb⁴, R. Moderski¹¹, E. Moulin¹⁰, M. Naumann-Godo¹⁴, M. de Naurois²⁴, D. Nedbal²⁵, D. Nekrassov¹, S. J. Nolan⁴, S. Ohm¹, J.-P. Olive⁵, E. de Oña Wilhelmi¹⁷, K. J. Orford⁴, J. L. Osborne⁴, M. Ostrowski²⁶, M. Panter¹, G. Pedaletti⁶, G. Pelletier¹³, P.-O. Petrucci¹³, S. Pita¹⁷, G. Pühlhofer⁶, M. Punch¹⁷, B. C. Raubenheimer¹², M. Raue⁷, S. M. Rayner⁴, M. Renaud¹, J. Ripken⁷, L. Rob²⁵, S. Rosier-Lees¹⁵, G. Rowell²⁷, B. Rudak¹¹, J. Ruppel²⁸, V. Sahakian³, A. Santangelo²², R. Schlickeiser²⁸, F. M. Schöck²⁰, R. Schröder²⁸, U. Schwanke⁸, S. Schwarzburg²², S. Schwemmer⁶, A. Shalchi²⁸, H. Sol⁹, D. Spangler⁴, L. Stawarz²⁶, R. Steenkamp²⁹, C. Stegmann²⁰, G. Superina¹⁴, P. H. Tam⁶, J.-P. Tavernet²⁴, R. Terrier¹⁷, C. van Eldik¹, G. Vasileiadis¹⁸, C. Venter¹², J. P. Vialle¹⁵, P. Vincent²⁴, M. Vivier¹⁰, H. J. Völk¹, F. Volpe^{14, 16}, S. J. Wagner⁶, M. Ward⁴, A. A. Zdziarski¹¹, and A. Zech<sup>9

1</sup>  Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
    e-mail: Karl.Kosack@mpi-hd.mpg.de
²  Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
³  Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
⁴  University of Durham, Department of Physics, South Road, Durham DH1 3LE, UK
⁵  Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, 9 Av. du Colonel Roche, BP 4346, 31029 Toulouse Cedex 4, France
⁶  Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
⁷  Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
⁸  Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
⁹  LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
¹⁰  DAPNIA/DSM/CEA, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
¹¹  Nicolaus Copernicus Astronomical Center, Warsaw, Poland
¹²  Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa
¹³  Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
¹⁴  Laboratoire Leprince-Ringuet, École Polytechnique, CNRS/ IN2P3, 91128 Palaiseau, France
¹⁵  Laboratoire d'Annecy-le-Vieux de Physique des Particules, CNRS/IN2P3, 9 chemin de Bellevue, BP 110, 74941 Annecy-le-Vieux Cedex, France
¹⁶  European Associated Laboratory for Gamma-Ray Astronomy, jointly supported by CNRS and MPG
¹⁷  Astroparticule et Cosmologie (APC), CNRS, Université Paris 7 Denis Diderot, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13; (UMR 7164 (CNRS, Université Paris VII, CEA, Observatoire de Paris)) , France
¹⁸  Laboratoire de Physique Théorique et Astroparticules, CNRS/IN2P3, Université Montpellier II, CC 70, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
    e-mail: Armand.Fiasson@LPTA.in2p3.fr
¹⁹  Kavli Institute for Particle Astrophysics and Cosmology, SLAC, 2575 Sand Hill Road, Menlo-Park, CA-94025, USA
²⁰  Universität Erlangen-Nürnberg, Physikalisches Institut, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
²¹  School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, UK
²²  Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
²³  Torun Centre for Astronomy, Nicolaus Copernicus University, Torun, Poland
²⁴  LPNHE, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, CNRS/IN2P3, 4 place Jussieu, 75252 Paris Cedex 5, France
²⁵  Institute of Particle and Nuclear Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
²⁶  Obserwatorium Astronomiczne, Uniwersytet Jagiellonski, Kraków, Poland
²⁷  School of Chemistry & Physics, University of Adelaide, Adelaide 5005, Australia
²⁸  Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
²⁹  University of Namibia, Private Bag 13301, Windhoek, Namibia

(Received 11 December 2007 / Accepted 20 February 2008)

Abstract
Aims. HESS J1745-303 is an extended, unidentified VHE (very high energy) gamma-ray source discovered using HESS in the Galactic Plane Survey. Since no obvious counterpart has previously been found in longer-wavelength data, the processes that power the VHE emission are not well understood.
Methods. Combining the latest VHE data with recent XMM-Newton observations and a variety of source catalogs and lower-energy survey data, we attempt to match (from an energetic and positional standpoint) the various parts of the emission of HESS J1745-303 with possible candidates.
Results. Though no single counterpart is found to fully explain the VHE emission, we postulate that at least a fraction of the VHE source may be explained by a supernova-remnant/molecular-cloud association and/or a high-spin-down-flux pulsar.

Key words: gamma rays: observations -- X-rays: general -- Galaxy: general -- ISM: cosmic rays -- ISM: clouds

© ESO 2008