For the first time within a multi-angle computational framework we investigate the time evolution of neutrino halo effects on collective neutrino oscillation (CNO) in an iron core-collapse supernova. For the collapse of the $9.6\, \rm M_\odot$ progenitor employed in this work, we find that there is a window of time where one can safely calculate CNO including the neutrino halo effects due to the density gradient of the envelope. The impact of inward-scattered neutrino flux on CNO can not be ignored inside the shock front, compared with the outward-propagating neutrino flux. However, there is a window of time where CNO is not shut down by multi-angle matter suppression and delayed in onset beyond the radius of the growing shock front. Halo neutrinos with wider intersection trajectories induce a delay for the onset radius of CNO, while they produce additional flavor conversion for neutrino spectra. This additional flavor conversion sharpens CNO spectral features, leading to a detected neutrino signal which is more clearly distinguishable from thermal emission than when halo neutrinos are omitted.

中文翻译：

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9.6 M⊙ 恒星铁核坍缩超新星模型中微子晕对集体中微子振荡的影响

我们首次在多角度计算框架内研究了中微子晕效应对铁核坍缩超新星中集体中微子振荡 (CNO) 的时间演化。对于这项工作中使用的 $9.6\, \rm M_\odot$ 前体的坍塌，我们发现有一个时间窗口，可以安全地计算 CNO，包括由于包络密度梯度引起的中微子晕效应。与向外传播的中微子通量相比，在激波前沿内部，向内散射的中微子通量对 CNO 的影响不容忽视。然而，有一个时间窗口，CNO 不会被多角度物质抑制关闭，并且会延迟到增长的激波前沿半径之外。具有更宽交叉轨迹的晕中微子会导致 CNO 起始半径的延迟，同时它们为中微子光谱产生额外的风味转换。这种额外的风味转换使 CNO 光谱特征更加清晰，从而导致检测到的中微子信号比省略晕中微子时更能与热辐射区分开来。