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arXiv 1305.4113astro-ph.HE
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来自IceCube扩展星系源的中微子信号

Neutrino signal from extended Galactic sources in IceCube

C. Tchernin, J. A. Aguilar, A. Neronov, T. Montaruli

摘要:

我们探索中微子通量的可探测性从整个银河平面或从它的一部分与冰立方。根据费米/LAT望远镜观测到的100 GeV以上能带的π介子衰变γ射线漫发射的光谱特征,计算了银河系平面不同区域中微子幂律谱的归一化和谱指数。我们用这种方法计算的中微子通量与IceCube探测扩展源的灵敏度进行了比较。假设一个binned扩展源分析方法,我们发现,位于北半球的源中微子排放的唯一可能的证据是从天鹅座地区曝光后20年。对于银河平面的其他部分,即使是20年的冰立方曝光也不足以探测到。考虑到天鹅座区域中可探测源的边缘意义,我们找到了一个精确的位置和源区的大小,优化了中微子的信噪比。我们还计算了中微子信号能以最高信噪比被探测到的低能阈值。这种基于γ射线数据的精确源位置、大小和能量范围的计算,可以用来消除在分析IceCube的真实中微子数据时的“试探因子”。我们注意到南半球内银道面的散射中微子辐射要亮得多。一个中微子探测器的特性与冰立方相当,但放置在北半球(如KM 3 NeT),将在5σ水平下在短短5年内探测到银河平面上的几个孤立的中微子源。这些孤立的~TeV中微子源将毫不含糊地定位在银河系过去一万年中运行的宇宙射线源。[删节]

英文摘要:

We explore the detectability of the neutrino flux from the entire Galactic Plane or from a part of it with IceCube. We calculate the normalization and the spectral index of the neutrino power law spectrum from different regions of the Galactic plane, based on the observed spectral characteristics of the pion decay gamma-ray diffuse emission observed by the Fermi/LAT telescope in the energy band above 100 GeV. We compare the neutrino flux calculated in this way with the sensitivity of IceCube for the detection of extended sources. Assuming a binned extended source analysis method, we find that the only possible evidence for neutrino emission for sources located in the Northern hemisphere is from the Cygnus region after 20 years of exposure. For other parts of the Galactic Plane even a 20 years exposure with IceCube is not sufficient for the detection. Taking into account marginal significance of the detectable source in the Cygnus region, we find a precise position and size of the source region which optimizes the signal-to-noise ratio for neutrinos. We also calculate the low-energy threshold above which the neutrino signal could be detected with the highest signal-to-noise ratio. This calculation of precise source position, size and energy range, based on the gamma-ray data, could be used to remove the 'trial factor' in the analysis of the real neutrino data of IceCube. We notice that the diffuse neutrino emission from the inner Galactic Plane in the Southern Hemisphere is much brighter. A neutrino detector with characteristics equivalent to IceCube, but placed at the Northern Hemisphere (such as KM3NeT), would detect several isolated neutrino sources in the Galactic Plane within just 5 years exposure at 5σ level. These isolated sources of ~TeV neutrinos would unambiguously localize sources of cosmic rays which operated over the last 10 thousand years in the Galaxy.[abridged]

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