Detection of very-high-energy γ-ray emission from the vicinity of PSR B1706–44 and G 343.1–2.3 with H.E.S.S.

¹ Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany ;
e-mail: ryan.chaves@mpi-hd.mpg.de
² Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
³ Centre d’Étude Spatiale des Rayonnements, CNRS/UPS, 9 Av. du Colonel Roche, BP 4346, 31029 Toulouse Cedex 4, France
⁴ Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
⁵ Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
⁶ LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 Place Jules Janssen, 92190 Meudon, France
⁷ CEA Saclay, DSM/IRFU, 91191 Gif-Sur-Yvette Cedex, France
⁸ University of Durham, Department of Physics, South Road, Durham DH1 3LE, UK
⁹ Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa
¹⁰ Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3, 91128 Palaiseau, France
¹¹ Laboratoire d’Annecy-le-Vieux de Physique des Particules, Université de Savoie, CNRS/IN2P3, 74941 Annecy-le-Vieux, France
¹² 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 )
¹³ Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
¹⁴ Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
¹⁵ Laboratoire de Physique Théorique et Astroparticules, Université Montpellier 2, CNRS/IN2P3, CC 70, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
¹⁶ Universität Erlangen-Nürnberg, Physikalisches Institut, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
¹⁷ Laboratoire d’Astrophysique de Grenoble, INSU/CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
¹⁸ Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
¹⁹ LPNHE, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, 75252 Paris Cedex 5, France
²⁰ Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
²¹ Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
²² University of Namibia, Department of Physics, Private Bag 13301, Windhoek, Namibia
²³ Obserwatorium Astronomiczne, UniwersytetJagielloński, ul. Orla 171, 30-244 Kraków, Poland
²⁴ Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland
²⁵ School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, UK
²⁶ School of Chemistry & Physics, University of Adelaide, 5005 Adelaide, Australia
²⁷ Toruń Centre for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87-100 Toruń, Poland
²⁸ Instytut Fizyki Ja¸drowej PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland
²⁹ Astronomical Observatory, The University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
³⁰ Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität Innsbruck, 6020 Innsbruck, Austria
³¹ Oskar Klein Centre, Department of Physics, Stockholm University, Albanova University Center, 10691 Stockholm, Sweden
³² Oskar Klein Centre, Department of Physics, Royal Institute of Technology (KTH), Albanova, 10691 Stockholm, Sweden
³³ Department of Physics and Astronomy, The University of Leicester, University Road, Leicester, LE1 7RH, UK
³⁵ National Academy of Sciences of the Republic of Armenia, Yerevan
³⁶ Université Bordeaux 1; CNRS/IN2P3; Centre d’Études Nuclaires de Bordeaux Gradignan, UMR 5797, Chemin du Solarium, BP120, 33175 Gradignan, France
³⁷ Instituto de Astronomia y Fisica del Espacio (CONICET-UBA), Buenos Aires, Argentina

Received: 12 July 2010
Accepted: 28 November 2010

Abstract

The γ-ray pulsar PSR B1706−44 and the adjacent supernova remnant (SNR) candidate G 343.1−2.3 were observed by H.E.S.S. during a dedicated observation campaign in 2007. As a result of this observation campaign, a new source of very-high-energy (VHE; E > 100 GeV) γ-ray emission, H.E.S.S. J1708−443, was detected with a statistical significance of 7σ, although no significant point-like emission was detected at the position of the energetic pulsar itself. In this paper, the morphological and spectral analyses of the newly-discovered TeV source are presented. The centroid of H.E.S.S. J1708−443 is considerably offset from the pulsar and located near the apparent center of the SNR, at α_J2000 = 17^h08^m11^s ± 17^s and δ_J2000 =  −44°20′ ± 4′. The source is found to be significantly more extended than the H.E.S.S. point spread function (~0.1°), with an intrinsic Gaussian width of 0.29°  ±  0.04°. Its integral flux between 1 and 10 TeV is  ~ 3.8 × 10^-12   ph   cm^-2   s^-1, equivalent to 17% of the Crab Nebula flux in the same energy range. The measured energy spectrum is well-fit by a power law with a relatively hard photon index Γ = 2.0  ±  0.1_stat  ±  0.2_sys. Additional multi-wavelength data, including 330 MHz VLA observations, were used to investigate the VHE γ-ray source’s possible associations with the pulsar wind nebula of PSR B1706−44 and/or with the complex radio structure of the partial shell-type SNR G 343.1−2.3.