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导的事件，它们在IceCube探测器中的估计沉积能量分别为1.0±0.15和1.1±0.17 PeV，这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受控的粒子簇射是一致的。这些事件是在搜索超高能中微子时发现的，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，仅背景假设的结果p值为2.8x10^-3(2.8σ)。这并不是超过PeV的天体物理中微子流量的第一个迹象。超高能宇宙线(UHECR)发射体在红移空间的分布受能量区中微子速率上限的限制。观测约束第一次到达了参数区域的起点，预计一些UHECR源领先候选者将分布在该区域。由于仪器体积的扩大和改进的蒙特卡罗模拟，边界比我们以前的出版物有了显著的升级。

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.