The New Frontier of Extreme-Astrophysics with the IceCube Neutrino Observatory

我们成功地观测到了两个中微子诱发事件，它们在IceCube探测器上的沉积能量估计分别为1.0 ± 0.15和1.1 ± 0.17PeV，是迄今为止观测到的最高能量。它们与IceCube探测器内中性电流nu-e、nu-mu或nu-tau或带电电流nu-e相互作用引起的完全包含的粒子簇射一致。这些事件是在寻找超高能中微子时发现的，使用的数据对应于615.9天的有效寿命。这两个中微子事件是在0.082±0.004（stat）+0.041 -0.057（sys）的预期大气背景下观测到的。考虑到背景事件预期数量的不确定性，仅背景假设的p值为2.8×10^<-3>（2.8σ）。这是第一个天体物理学中微子流量超过PeV的迹象。在100 PeV以上的能量区域的中微子速率的上限限制了超高能宇宙射线（UHECR）发射体在红移空间中的分布。观测约束首次到达参数区域的开始，预计将分布一些UHECR源领先的候选人。由于扩大的仪器体积和精细的Monte Carlo模拟，我们以前的出版物的界限显着升级。

We successfully made the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.0 ± 0.15 and 1.1 ± 0.17PeV, respectively, the highest energies observed so far. They are consistent with fully contained particle showers induced by neutral-current nu-e, nu-mu or nu-tau, or charged-current nu-e interactions within the IceCube detector. The events were discovered in a search for ultra-high energy neutrinos using data corresponding to615.9 days effective livetime. The two neutrino events are observed over an expected atmospheric background of 0.082±0.004(stat)+0.041 -0.057(sys). The resulting p-value for the background-only hypothesis is 2.8×10^<-3> (2.8σ) taking into account the uncertainty on the expected number of background events. This is t a first indication ofan astrophysical neutrino flux beyond PeV. An upper limit on the neutrino rate in the energy region above 100 PeV puts constraints on distribution of ultra-high energy cosmic-ray (UHECR) emitters in redshift space. For the first time the observational constraints reach the beginning of the parameter region where some UHECR source leading candidates are expected to be distributed. The bound is significantly upgraded from our previous publication because of the enlarged instrumentation volume and refined Monte Carlo simulations.