Evidence for Proton Acceleration up to TeV Energies Based on VERITAS and Fermi-LAT Observations of the Cas A SNR
Evidence for Proton Acceleration up to TeV Energies Based on VERITAS and Fermi-LAT Observations of the Cas A SNR
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DOI：
10.3847/1538-4357/ab8310
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
A. Abeysekara;A. Archer;W. Benbow;R. Bird;R. Brose;M. Buchovecky;J. Buckley;A. Chromey;W. Cui-W
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文献类型：
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作者：
A. Abeysekara;A. Archer;W. Benbow;R. Bird;R. Brose;M. Buchovecky;J. Buckley;A. Chromey;W. Cui-W
本文研究了核心坍缩超新星遗迹Cas A在0.1 GeV ~ 10 TeV能量范围内的γ射线辐射。我们使用了65小时的甚高能辐射成像望远镜阵列系统（VERITAS）的数据，覆盖200 GeV-10 TeV，和10.8年的费米大面积望远镜（LAT）的数据，覆盖0.1-500 GeV。Fermi-LAT数据的光谱分析表明，在1.3 ± 0.4统计GeV附近有一个明显的光谱曲率，这与π介子衰变的预期光谱一致。在这个能量以上，费米-LAT和VERITAS的联合光谱明显偏离了简单的幂律，最好用光谱指数为2.17 ± 0.02stat，截止能量为2.3 ± 0.5stat TeV的幂律来描述。这些结果，沿着无线电，X射线和γ射线的数据，在轻子和强子模型的背景下解释。假设一个单区模型，我们排除了一个纯粹的轻子的情况下，并得出结论，质子加速至少6 TeV的解释所观察到的γ射线谱。通过对整个多波长光谱的建模，推导出了Bmin <$150 μG残留物内的最小磁场。
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 μG is deduced.