OBSERVATION AND CHARACTERIZATION OF A COSMIC MUON NEUTRINO FLUX FROM THE NORTHERN HEMISPHERE USING SIX YEARS OF ICECUBE DATA
OBSERVATION AND CHARACTERIZATION OF A COSMIC MUON NEUTRINO FLUX FROM THE NORTHERN HEMISPHERE USING SIX YEARS OF ICECUBE DATA
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DOI：
10.3847/0004-637x/833/1/3
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发表时间：
2016-12-10
影响因子：
4.9
通讯作者：
Zoll, M.
中科院分区：
文献类型：
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作者：
Aartsen, M. G.;Abraham, K.;Zoll, M.
IceCube合作先前发现了一个高能天体物理中微子通量，使用中微子事件，其相互作用顶点包含在IceCube探测器的仪器体积内。我们提出了一个互补的测量使用带电电流μ介子中微子事件的相互作用顶点可以在这个体积之外。由于μ介子的射程很大，有效区域明显更大，但视场仅限于北方半球。从2009年到2015年的IceCube数据已经使用基于重建的μ子能量和天顶角的可能性方法进行了分析。在194 TeV和7.8 PeV之间的最高中微子能量的一个显着的天体物理学的贡献被观察到，不包括一个纯粹的大气起源这些事件在5.6西格玛的意义。这些数据可以用各向同性的、不间断的幂律通量来描述，在100 TeV中微子能量下归一化为（0.90（-0.27）（+0.30））x 10（-18）GeV-1 cm（-2）s（-1）sr（-1），硬谱指数为伽马= 2.13 +/- 0.13。观测到的光谱比以前的冰立方分析更难，能量阈值更低，这可能表明天体物理中微子光谱中有一个未知来源的中断。观测到的最高能量事件具有重建的μ子能量（4.5 +/- 1.2）PeV，这意味着该事件是大气起源的概率小于0.005%。分析所有事件的到达方向与重建的μ子能量超过200 TeV没有相关性与已知的γ射线sources. Using大气中微子的高统计，我们报告了目前最好的约束，对一个提示大气μ子中微子通量起源于粲介子衰变是低于1.06的单位的通量归一化的模型在Enberg等人。
The IceCube Collaboration has previously discovered a high-energy astrophysical neutrino flux using neutrino events with interaction vertices contained within the instrumented volume of the IceCube detector. We present a complementary measurement using charged current muon neutrino events where the interaction vertex can be outside this volume. As a consequence of the large muon range the effective area is significantly larger but the field of view is restricted to the Northern Hemisphere. IceCube data from 2009 through 2015 have been analyzed using a likelihood approach based on the reconstructed muon energy and zenith angle. At the highest neutrino energies between 194 TeV and 7.8 PeV a significant astrophysical contribution is observed, excluding a purely atmospheric origin of these events at 5.6 sigma significance. The data are well described by an isotropic, unbroken power-law flux with a normalization at 100 TeV neutrino energy of (0.90(-0.27)(+0.30)) x 10(-18) GeV-1 cm(-2) s(-1) sr(-1) and a hard spectral index of gamma = 2.13 +/- 0.13. The observed spectrum is harder in comparison to previous IceCube analyses with lower energy thresholds which may indicate a break in the astrophysical neutrino spectrum of unknown origin. The highest-energy event observed has a reconstructed muon energy of (4.5 +/- 1.2) PeV which implies a probability of less than 0.005% for this event to be of atmospheric origin. Analyzing the arrival directions of all events with reconstructed muon energies above 200 TeV no correlation with known gamma-ray sources was found. Using the high statistics of atmospheric neutrinos we report the current best constraints on a prompt atmospheric muon neutrino flux originating from charmed meson decays which is below 1.06 in units of the flux normalization of the model in Enberg et al.