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Abeysekara, A. U.; Archer, A.; Benbow, W.; Bird, R.; Brose, R.; Buchovecky, M.; Buckley, J. H.; Chromey, A. J.; Cui, W.; Daniel, M. K.; Das, S.; Dwarkadas, V. V.; Falcone, A.; Feng, Q.; Finley, J. P.; Fortson, L.; Gent, A.; Gillanders, G. H.; Giuri, C.; Gueta, O.; Hanna, D.; Hassan, T.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Maier, G.; Moriarty, P.; Mukherjee, R.; Nievas-Rosillo, M.; O'Brien, S.; Ong, R. A.; Park, N.; Petrashyk, A.; Pfrang, K.; Pohl, M.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Sushch, I.; Weinstein, A.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Williamson, T. J; Zitzer, B.; Ghiotto, A.
Astrophysical journal/The Astrophysical journal, 05/2020, Letnik: 894, Številka: 1Journal Article
We present a study of γ-ray emission from the core-collapse supernova remnant Cas A in the energy range from 0.1 GeV to 10 TeV. We used 65 hr of the Very Energetic Radiation Imaging Telescope Array System (VERITAS) data to cover 200 GeV-10 TeV, and 10.8 yr of Fermi-Large Area Telescope (LAT) data to cover 0.1-500 GeV. The spectral analysis of Fermi-LAT data shows a significant spectral curvature around 1.3 0.4stat GeV that is consistent with the expected spectrum from pion decay. Above this energy, the joint spectrum from Fermi-LAT and VERITAS deviates significantly from a simple power law, and it is best described by a power law with a spectral index of 2.17 0.02stat and a cutoff energy of 2.3 0.5stat TeV. These results, along with radio, X-ray, and γ-ray data, are interpreted in the context of leptonic and hadronic models. Assuming a one-zone model, we exclude a purely leptonic scenario and conclude that proton acceleration up to at least 6 TeV is required to explain the observed γ-ray spectrum. From modeling of the entire multiwavelength spectrum, a minimum magnetic field inside the remnant of Bmin 150 G is deduced.
