Detailed spectral and morphological analysis of the shell type supernova remnant RCW 86

¹ Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
² Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
³ Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
⁴ National Academy of Sciences of the Republic of Armenia, Marshall Baghramian Avenue, 24, 0019 Yerevan, Republic of Armenia
⁵ Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
⁶ Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
⁷ University of Namibia, Department of Physics, Private Bag 13301, Windhoek, Namibia
⁸ GRAPPA, Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
⁹ Department of Physics and Electrical Engineering, Linnaeus University, 351 95 Växjö, Sweden
¹⁰ Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
¹¹ GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
¹² Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität Innsbruck, 6020 Innsbruck, Austria
¹³ School of Chemistry & Physics, University of Adelaide, 5005 Adelaide, Australia
¹⁴ Centre for Space Research, North-West University, 2520 Potchefstroom, South Africa
¹⁵ LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 Place Jules Janssen, 92190 Meudon, France
¹⁶ LPNHE, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, 75252 Paris, Cedex 5, France
¹⁷ Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS/IN2P3, CC 72, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
¹⁸ DSM/Irfu, CEA Saclay, 91191 Gif-Sur-Yvette Cedex, France
¹⁹ Astronomical Observatory, The University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
²⁰ Aix Marseille Universié, CNRS/IN2P3, CPPM UMR 7346, 13288 Marseille, France
²¹ Instytut Fizyki Ja̧drowej PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland
²² Funded by EU FP7 Marie Curie, grant agreement No. PIEF-GA-2012-332350
²³ School of Physics, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, 2050 Johannesburg, South Africa
²⁴ Laboratoire d’Annecy-le-Vieux de Physique des Particules, Université Savoie Mont-Blanc, CNRS/IN2P3, 74941 Annecy-le-Vieux, France
²⁵ Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
²⁶ Université Bordeaux, CNRS/IN2P3, Centre d’Études Nucléaires de Bordeaux Gradignan, 33175 Gradignan, France
²⁷ Oskar Klein Centre, Department of Physics, Stockholm University, Albanova University Center, 10691 Stockholm, Sweden
²⁸ Wallenberg Academy Fellow
²⁹ Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
³⁰ Laboratoire Leprince-Ringuet, École Polytechnique, CNRS/IN2P3, 91128 Palaiseau, France
³¹ APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
³² Univ. Grenoble Alpes, IPAG; CNRS, IPAG, 38000 Grenoble, France
³³ Department of Physics and Astronomy, The University of Leicester, University Road, Leicester, LE1 7RH, UK
³⁴ Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland
³⁵ Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
³⁶ DESY, 15738 Zeuthen, Germany
³⁷ Obserwatorium Astronomiczne, Uniwersytet Jagielloński, ul. Orla 171, 30-244 Kraków, Poland
³⁸ Universität Erlangen-Nürnberg, Physikalisches Institut, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
³⁹ Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland
⁴⁰ Department of Physics, University of the Free State, PO Box 339, 9300 Bloemfontein, South Africa
⁴¹ Heisenberg Fellow (DFG), ITA Universität Heidelberg, 69117 Heidelberg, Germany
⁴² GRAPPA, Institute of High-Energy Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands

^★ Corresponding author: H.E.S.S. Collaboration, e-mail: contact.hess@hess-experiment.eu

Received: 18 May 2015
Accepted: 9 November 2015

Abstract

Aim. We aim for an understanding of the morphological and spectral properties of the supernova remnant RCW 86 and for insights into the production mechanism leading to the RCW 86 very high-energy γ-ray emission.

Methods. We analyzed High Energy Spectroscopic System (H.E.S.S.) data that had increased sensitivity compared to the observations presented in the RCW 86 H.E.S.S. discovery publication. Studies of the morphological correlation between the 0.5–1 keV X-ray band, the 2–5 keV X-ray band, radio, and γ-ray emissions have been performed as well as broadband modeling of the spectral energy distribution with two different emission models.

Results. We present the first conclusive evidence that the TeV γ-ray emission region is shell-like based on our morphological studies. The comparison with 2–5 keV X-ray data reveals a correlation with the 0.4–50 TeV γ-ray emission. The spectrum of RCW 86 is best described by a power law with an exponential cutoff at E_cut = (3.5 ± 1.2_stat) TeV and a spectral index of Γ ≈ 1.6 ± 0.2. A static leptonic one-zone model adequately describes the measured spectral energy distribution of RCW 86, with the resultant total kinetic energy of the electrons above 1 GeV being equivalent to ~0.1% of the initial kinetic energy of a Type Ia supernova explosion (10⁵¹ erg). When using a hadronic model, a magnetic field of B ≈ 100 μG is needed to represent the measured data. Although this is comparable to formerly published estimates, a standard E⁻² spectrum for the proton distribution cannot describe the γ-ray data. Instead, a spectral index of Γ_p ≈ 1.7 would be required, which implies that ∼7 × 10⁴⁹/n_cm⁻³ has been transferred into high-energy protons with the effective density n_cm⁻³ = n/1 cm⁻³. This is about 10% of the kinetic energy of a typical Type Ia supernova under the assumption of a density of 1 cm⁻³.