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

我们成功地观测到两个中微子诱导事件，估计它们在冰立方探测器中的沉积能量分别为1.0±0.15和1.1±0.17PeV，这是迄今为止观测到的最高能量。它们与冰立方探测器内由中性电流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阵雨一致。这些事件是在对超高能量中微子的搜索中发现的，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）的预期大气背景上观测到的。考虑到期望背景事件数的不确定性，仅背景假设的所得p值为2.8×10^<-3> (2.8σ)。这是第一个天体物理中微子通量超过PeV的迹象。100 PeV以上能量区的中微子速率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。观测约束首次到达了一些UHECR源领先候选者预计分布的参数区域的开始。由于仪器体积的扩大和蒙特卡罗模拟的改进，该边界从我们以前的出版物中得到了显着升级。

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.