We report on observations of very high energy γ rays from the shell-type supernova remnant (SNR) Cassiopeia A with the Very Energetic Radiation Imaging Telescope Array System stereoscopic array of four imaging atmospheric Cherenkov telescopes in Arizona. The total exposure time for these observations is 22 hr, accumulated between September and November of 2007. The γ-ray source associated with the SNR Cassiopeia A was detected above 200 GeV with a statistical significance of 8.3σ. The estimated integral flux for this γ-ray source is about 3% of the Crab-Nebula flux. The photon spectrum is compatible with a power law dN/dE ∝ E –Γ with an index Γ = 2.61 ± 0.24stat ± 0.2sys. The data are consistent with a point-like source. We provide a detailed description of the analysis results and discuss physical mechanisms that may be responsible for the observed γ-ray emission.
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机译：我们报告了非常高能辐射成像望远镜阵列系统的立体成像，由亚利桑那州的四个成像大气Cherenkov望远镜从壳型超新星遗留（SNR）仙后座A观察到的非常高能量的γ射线。这些观测的总曝光时间为22小时，在2007年9月至11月之间累积。在200 GeV以上检测到与SNR仙后座A相关的γ射线源，其统计显着性为8.3σ。该γ射线源的估计积分通量约为蟹状星云通量的3％。光子光谱与幂律dN / dE ∝ E –Γ兼容，折射率Γ= 2.61±0.24stat±0.2sys。数据与点状源一致。我们提供了分析结果的详细说明，并讨论了可能导致观察到的γ射线发射的物理机制。
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