论文标题
$λ$ CDM的两种冷液的宇宙学扰动
Cosmological perturbations for two cold fluids in $Λ$CDM
论文作者
论文摘要
我们宇宙的宇宙大规模结构由重子和冷暗物质（CDM）组成。然而，习惯上，将这两个组件视为具有消失压力的联合单分体流体，这仅适用于足够大的尺度和较晚的时间。在这里，我们超越了单流体近似值，并开发了两个重力耦合流体的扰动理论，同时仍假设压力消失。我们主要专注于$ d $（或$ d _+$）的扰动扩展，这是物质在$λ$ CDM宇宙中的线性结构增长，具有宇宙常数$λ$。我们尤其是（1）对两种流体密度的显式递归关系，（2）在拉格朗日坐标方法中互补的全阶结果，以及（3）（3）在宇宙宇宙大小尺度结构的半经典方法中相关的组件波函数。在我们的同伴论文（Hahn等，2020）中，我们应用了这些新的理论结果来为宇宙学水动力学模拟生成新颖的高阶初始条件。
The cosmic large-scale structure of our Universe is comprised of baryons and cold dark matter (CDM). Yet it is customary to treat these two components as a combined single-matter fluid with vanishing pressure, which is justified only for sufficiently large scales and late times. Here we go beyond the single-fluid approximation and develop the perturbation theory for two gravitationally coupled fluids while still assuming vanishing pressure. We mostly focus on perturbative expansions in powers of $D$ (or $D_+$), the linear structure growth of matter in a $Λ$CDM Universe with cosmological constant $Λ$. We derive in particular (1) explicit recursion relations for the two fluid densities, (2) complementary all-order results in the Lagrangian-coordinates approach, as well as (3) the associated component wavefunctions in a semi-classical approach to cosmic large-scale structure. In our companion paper (Hahn et al. 2020) we apply these new theoretical results to generate novel higher-order initial conditions for cosmological hydrodynamical simulations.
