Deep morphological and spectral study of the SNR RCW 86 with Fermi-LAT
de, Palma F
Di, Lalla N
Di, Mauro M
Di, Venere L
Institute of Physics
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Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Bloom, E., et al. (2016). Deep morphological and spectral study of the SNR RCW 86 with Fermi-LAT. Astrophysical Journal, 819 (98)https://doi.org/10.3847/0004-637X/819/2/98
RCW 86 is a young supernova remnant (SNR) showing a shell-type structure at several wavelengths and is thought to be an efficient cosmic-ray (CR) accelerator. Earlier Fermi Large Area Telescope results reported the detection of γ-ray emission coincident with the position of RCW 86 but its origin (leptonic or hadronic) remained unclear due to the poor statistics. Thanks to 6.5 years of data acquired by the Fermi-LAT and the new event reconstruction Pass 8, we report the significant detection of spatially extended emission coming from RCW 86. The spectrum is described by a power-law function with a very hard photon index (Γ = 1.42 ± 0.1_stat ± 0.06_syst) in the 0.1–500 GeV range and an energy flux above 100 MeV of (2.91 ± 0.8_stat ± 0.12_syst) × 10⁻¹¹ erg cm⁻² s ⁻¹ . Gathering all the available multiwavelength (MWL) data, we perform a broadband modeling of the nonthermal emission of RCW 86 to constrain parameters of the nearby medium and bring new hints about the origin of the γ-ray emission. For the whole SNR, the modeling favors a leptonic scenario in the framework of a two-zone model with an average magnetic field of 10.2 ± 0.7 µG and a limit on the maximum energy injected into protons of 2 × 10⁴⁹ erg for a density of 1 cm⁻³ . In addition, parameter values are derived for the North-East (NE) and South-West (SW) regions of RCW 86, providing the first indication of a higher magnetic field in the SW region.
The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique / Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. GD and EG are members of CIC-CONICET (Argentina), LD is Fellow of CONICET (Argentina). They are supported through grants from CONICET and ANPCyT (Argentina). We acknowledge to Estela Reynoso and Anne Green who collaborated in the first stages of the HI data acquisition and preocessing.
External DOI: https://doi.org/10.3847/0004-637X/819/2/98
This record's URL: https://www.repository.cam.ac.uk/handle/1810/253526