After decoupling, relic neutrinos traverse the evolving gravitational imhomogeneities along their trajectories. Once they turn non-relativistic, this results in a significant amplification of the anisotropies in the cosmic neutrino background (CνB). Past studies have reconstructed the phase-space distribution of relic neutrinos from the local distribution of matter (accounting for the Milky Way halo and the surrounding large-scale structures), but have neglected the CνB anisotropies in the initial conditions of neutrino trajectories. Using our previously developed N-1-body simulation framework, we show that including these primordial fluctuations in the initial conditions can be important, as it produces similar effects on the abundance and anisotropies of the CνB as the inclusion of large-scale structures beyond the Milky Way halo. Interpretability of data from future CνB observatories like PTOLEMY therefore depends on correctly modelling these effects. GitHub: our jax-accelerated simulation code can be found here.

中文翻译：

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原始涨落对遗留中微子模拟的影响


解耦后，遗留中微子沿着其轨迹穿过不断发展的引力不均匀性。一旦它们变成非相对论的，这会导致宇宙中微子背景 （CνB） 中的各向异性显着放大。过去的研究从物质的局部分布（解释了银河系晕和周围的大尺度结构）重建了遗迹中微子的相空间分布，但忽略了中微子轨迹初始条件下的 CνB 各向异性。使用我们之前开发的 N-1 体模拟框架，我们表明在初始条件中包含这些原始波动可能很重要，因为它对 CνB 的丰度和各向异性产生的影响与包含银河系晕以外的大尺度结构类似。因此，来自未来 CνB 天文台（如 PTOLEMY）的数据的可解释性取决于正确建模这些效应。GitHub：我们的 jax 加速模拟代码可以在这里找到。