The cosmic neutrino background is an important component of the universe that is difficult to include in cosmological simulations due to the extremely large velocity dispersion of neutrino particles. We develop a new approach to simulate cosmic neutrinos that decomposes the Fermi–Dirac phase space into shells of constant speed and then evolves those shells using hydrodynamic equations. These collisionless hydrodynamic equations have fluxes that match linear theory but retain the full nonlinear gravitational source terms. We implement this method into the information-optimized cosmological N -body code CUBE and demonstrate that neutrino perturbations can be accurately resolved to at least k ∼ 1 h Mpc −1 . This technique allows for neutrino memory requirements to be decreased by up to ##IMG## [http://ej.iop.org/images/0067-0049/250/1/21/apjsaba0b3ieqn1.gif] {$\sim {10}^{3}$} compared to traditional N -body methods.

中文翻译：

---

使用无碰撞流体动力学模拟宇宙中微子背景

宇宙中微子背景是宇宙的重要组成部分，由于中微子粒子的极快的速度散布，很难包含在宇宙学模拟中。我们开发了一种模拟宇宙中微子的新方法，该方法将费米-狄拉克相空间分解成恒速壳，然后使用流体动力学方程式演化这些壳。这些无碰撞流体动力学方程的通量与线性理论相符，但保留了全部非线性重力源项。我们将这种方法应用于信息优化的宇宙N体代码CUBE中，并证明中微子扰动可以准确地解析到至少k〜1 h Mpc -1。该技术允许中微子的内存需求最多减少## IMG ## [http：//ej.iop。