使用IceCube测量银河系平面沿线各段的中微子通量
Measuring the Neutrino Flux in Segments along the Galactic Plane with IceCube
AI总结：
本研究利用IceCube全天级联数据集，通过在银河经度上分段并采用非分箱极大似然分析分别拟合谱指数与通量归一化，提供了对银河系平面中微子辐射变化的模型无关见解。
摘要：
来自银河系平面的伽马射线辐射被认为部分源于宇宙射线与星际介质的相互作用。同样的相互作用预计会产生相应的中微子通量。2023年，IceCube以4.5σ置信水平报告了首次观测到这种银河中微子通量。该分析依赖于基于伽马射线观测的中微子通量预测，以模拟银河系平面的预期中微子辐射。测试了描述不同可能空间和能量分布的三种信号假设，其中每次测试中唯一的自由参数是中微子通量的归一化。我们展示了一项分析的初步结果，该分析通过在银河经度上将银河系平面划分为多个段，能够改进对银河中微子辐射的表征。使用非分箱极大似然分析，可以在每个段中分别拟合谱指数和通量归一化。虽然伽马射线望远镜无法区分强子和轻子辐射，但中微子的产生必然来自强子过程。测量谱指数可进一步帮助理解银河系平面内未解析中微子源的贡献。本工作使用全天级联数据集，为银河系平面不同区域的中微子通量和能量分布的变化提供了模型无关的见解。
英文摘要：
Gamma-ray emission from the plane of the Milky Way is understood as partly originating from the interaction of cosmic rays with the interstellar medium. The same interaction is expected to produce a corresponding flux of neutrinos. In 2023, IceCube reported the first observation of this galactic neutrino flux at 4.5$σ$ confidence level. The analysis relied on neutrino flux predictions - based on gamma ray observations - to model the expected neutrino emission from the galactic plane. Three signal hypotheses describing different possible spatial and energy distributions were tested, where the single free parameter in each test was the normalization of the neutrino flux. We present first results of an analysis that can improve the characterization of Galactic neutrino emission by dividing the galactic plane into segments in galactic longitude. An unbinned maximum-likelihood analysis is used that can fit the spectral index and the flux normalization separately in each segment. While gamma ray telescopes can not differentiate between hadronic and leptonic emission, neutrino production must come from hadronic processes. Measuring a spectral index can further help to understand the contribution of unresolved neutrino sources inside the galactic plane. This work uses a full-sky cascade dataset and provides model-independent insight into the variation of the neutrino flux and energy distribution from different regions of the galactic plane.
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