Evidence for Proton Acceleration up to TeV Energies Based on VERITAS and Fermi-LAT Observations of the Cas A SNR

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...

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Bibliographic Details
Published in:The Astrophysical journal 2020-05, Vol.894 (1), p.51
Main Authors: 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.
Format: Article
Language:English
Subjects:
Astrophysics
Emission analysis
Galactic cosmic rays
Gamma emission
Gamma-ray astronomy
Ground-based astronomy
Leptons
Magnetic fields
Observational astronomy
Pions
Power law
Protons
Radiation
Spectra
Spectral analysis
Spectrum analysis
Supernova
Supernova remnants
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Summary: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.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab8310