论文标题
Protohalos的相空间结构：Vlasov与粒子网
Phase-space structure of protohalos: Vlasov versus Particle-Mesh
论文作者
论文摘要
使用具有三个正弦波和冷暗物质（CDM）初始条件的宇宙学模拟来重新审视原始暗物质光环的相空间结构。这些模拟是通过基于镶嵌的Vlasov solver Coldice和粒子网（PM）$ n $ body代码进行的。分析包括投影密度，相空间图，径向密度和伪相空间密度。特别关注武力和质量分辨率。由于相位空间板的复杂性（根据总体积和简易程度计数）的数量估计，很快就会增加，因此Coldice只能遵循Halo形成的早期暴力放松阶段。在后者期间，Coldice和PM模拟之间具有一个粒子或更多粒子的一致性是极好的，Halos具有幂律密度曲线，$ρ（r）\ propto r^{ - α} $，$α\ in [1.5,1.8] $。在任何合并之前测量的斜率比文献略大。相位图在正弦波模拟中具有清晰的自相似性签名的相一致性模式，而CDM光晕在某种程度上有些简洁。在进行额外的质量分辨率测试之后，使用PM模拟遵循进化的下一个阶段。该幂律以密度曲线的收敛性逐渐分解为众所周知的“ NFW”类似的通用吸引子，无论初始条件如何，即使在三丝波模拟中也是如此。这再次表明合并并不代表与动态吸引子收敛的必要条件。毫不奇怪，测得的伪相空间密度是一个幂律$ q（r）\ propto r^{ - α_q} $，带有$α_ {\ rm q} $接近二级球形输入模型的预测，$α_{\ rm q}} \ rm q} \ simeq 1.875 $。但是，在早期放松阶段也验证了该特性，这是微不足道的。
The phase-space structure of primordial dark matter halos is revisited using cosmological simulations with three sine waves and Cold Dark Matter (CDM) initial conditions. The simulations are performed with the tessellation based Vlasov solver ColDICE and a Particle-Mesh (PM) $N$-body code. The analyses include projected density, phase-space diagrams, radial density and pseudo-phase space density. Particular attention is paid to force and mass resolution. Because the phase-space sheet complexity, estimated in terms of total volume and simplices count, increases very quickly, ColDICE can follow only the early violent relaxation phase of halo formation. During the latter, agreement between ColDICE and PM simulations having one particle per cell or more is excellent and halos have a power-law density profile, $ρ(r) \propto r^{-α}$, $α\in [1.5,1.8]$. This slope, measured prior to any merger, is slightly larger than in the literature. The phase-space diagrams evidence complex but coherent patterns with clear signatures of self-similarity in the sine wave simulations, while the CDM halos are somewhat scribbly. After additional mass resolution tests, the PM simulations are used to follow the next stages of evolution. The power-law progressively breaks down with a convergence of the density profile to the well known "NFW"-like universal attractor, irrespectively of initial conditions, that is even in the three-sine wave simulations. This demonstrates again that mergers do not represent a necessary condition for convergence to the dynamical attractor. Not surprisingly, the measured pseudo phase-space density is a power-law $Q(r) \propto r^{-α_Q}$, with $α_{\rm Q}$ close to the prediction of secondary spherical infall model, $α_{\rm Q} \simeq 1.875$. However this property is also verified during the early relaxation phase, which is non trivial.
