DEEP MORPHOLOGICAL and SPECTRAL STUDY of the SNR RCW 86 with FERMI-LAT

Ajello,; and Baldini, M.; and Barbiellini, L.; and Bastieri, G.; and Bellazzini, D.; and Bissaldi, R.; and Bloom, E.; and Bonino, E. D.; and Bottacini, R.; and Brandt, E.; and Bregeon, T. J.; and Bruel, J.; and Buehler, P.; and Caliandro, R.; and Cameron, G. A.; and Caragiulo, R. A.; and Cavazzuti, M.; and Charles, E.; and Chekhtman, E.; and Ciprini, A.; and Cohen-Tanugi, S.; and Condon, J.; and Costanza, B.; and Cutini, F.; and D'Ammando, S.; and Palma, F.; and Desiante, F. D.; and Lalla, R.; and Mauro, N. D.; and Venere, M. D.; and Drell, L. D.; and Dubner, P. S.; and Dumora, G.; and Duvidovich, D.; and Favuzzi, L.; and Focke, C.; and Fusco, W. B.; and Gargano, P.; and Gasparrini, F.; and Giacani, D.; and Giglietto, E.; and Glanzman, N.; and Green, T.; and Grenier, D. A.; and Guiriec, I. A.; and Hays, S.; and Hewitt, E.; and Hill, J. W.; and Horan, A. B.; and Jogler, D.; and Jóhannesson, T.; and Jung-Richardt, G.; and Kensei, I.; and Kuss, S.; and Larsson, M.; and Latronico, S.; and Lemoine-Goumard, L.; and Li, M.; and Li, J.; and Longo, L.; and Loparco, F.; and Lovellette, F.; and Lubrano, M. N.; and Magill, P.; and Maldera, J.; and Manfreda, S.; and Mayer, A.; and Mazziotta, M.; and McEnery, M. N.; and Michelson, J. E.; and Mitthumsiri, P. F.; and Mizuno, W.; and Monzani, T.; and Morselli, M. E.; and Moskalenko, A.; and Negro, I. V.; and Nuss, M.; and Orienti, E.; and Orlando, M.; and Ormes, E.; and Paneque, J. F.; and Perkins, D.; and Pesce-Rollins, J. S.; and Piron, M.; and Pivato, F.; and Porter, G.; and Rainò, T. A.; and Rando, S.; and Razzano, R.; and Reimer, M.; and Reimer, A.; and Reposeur, O.; and Schmid, T.; and Schulz, J.; and Sgrò, A.; and Simone, C.; and Siskind, D.; and Spada, E. J.; and Spandre, F.; and Spinelli, G.; and Thayer, P.; and Tibaldo, J. B.; and Torres, L.; D. F.,; Tosti, G.; Troja, And; and Uchiyama, E.; and Vianello, Y.; and Vink, G.; and Wood, J.; and Yassine, K. S.

doi: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 in the 0.1-500 GeV range and an energy flux above 100 MeV of 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 and south-west (SW) regions of RCW 86, providing the first indication of a higher magnetic field in the SW region. © 2016. The American Astronomical Society. All rights reserved.