论文标题
部分可观测时空混沌系统的无模型预测
Shape, alignment, and mass distribution of baryonic and dark-matter halos in one EAGLE simulation
论文作者
论文摘要
对光环的形态及其进化的准确知识是银河形成模型的关键约束以及强镜现象的决定性参数。使用宇宙学流体动力模拟，星系及其环境的演化和组装（Eagle），我们旨在对星系光环的形态及其质量分布的演变进行全面分析，并重点介绍了Redshift $ Z = 0.5 $的快照。我们制定了一种涉及主成分分析（PCA）的迭代策略，以研究鹰晕的特性以及各个组件之间的对齐差异。深色物质（DM），气体和星形光晕的质量分布的特征是半质量半径，浓度参数和（投影）轴比。我们介绍了336 \的形状参数的统计信息，来自Eagle Refl0025N0376模拟的540 Halos，并描述它们从Redshift $ z = 15 $到$ z = 0 $的演变。我们测量了DM，气体和恒星组件以及所有颗粒的三维和二维投影形状参数。在$ z = 0.5 $的情况下，气体的次要轴与DM的次要轴对齐（$ M> 10^{12} $ M $ _ \ odot $），但是对于较少的大量晕孔而言，这种对齐方式较差。 DM光晕轴比率$ b/a $和$ c/a $的中位数为$ 0.82 \ pm 0.11 $和$ 0.64 \ pm 0.12 $。带有光环和W/ O星的气体的球形似乎与总质量呈负相关，而DM的球体对其不敏感。 $ z = 0.5 $的星形光环的测得的投影轴比为$ b_p/a_p $的中位数为$ 0.80 \ pm 0.07 $，这与1 $σ$以内的基于地面和空间的测量值非常一致。对于DM Halos，我们的价值为$ 0.85 \ pm 0.06 $。
Accurate knowledge of the morphology of halos and its evolution are key constraints on the galaxy formation model as well as a determinant parameter of the strong-lensing phenomenon. Using the cosmological hydrodynamic simulation, the Evolution and Assembly of GaLaxies and their Environments (EAGLE), we aim to provide a comprehensive analysis of the evolution of the morphology of galaxy halos and of their mass distributions with a focus on the snapshot at redshift $z=0.5$. We developed an iterative strategy involving a principal component analysis (PCA) to investigate the properties of the EAGLE halos and the differences in alignment between the various components. The mass distributions of the dark-matter (DM), gas, and star halos are characterised by a half-mass radius, a concentration parameter and (projected) axis ratios. We present statistics of the shape parameters of 336\,540 halos from the EAGLE RefL0025N0376 simulation and describe their evolution from redshift $z=15$ to $z=0$. We measured the three-dimensional and two-dimensional projected shape parameters for the DM, the gas, and the star components as well as for all particles. At $z=0.5$, the minor axis of gas aligns with the minor axis of DM for massive halos ($M>10^{12}$ M$_\odot$), but this alignment is poorer for less massive halos. The DM halos axis ratios $b/a$ and $c/a$ have median values of $0.82 \pm 0.11$ and $0.64 \pm 0.12$, respectively. The sphericity of gas in halos w/ and w/o stars appears to be negatively correlated to the total mass, while the sphericity of DM is insensitive to it. The measured projected axis ratios, $b_p/a_p$, of star halos at $z=0.5$ have a median value of $0.80 \pm 0.07$, which is in good agreement with ground-based and space-based measurements within 1 $σ$. For DM halos, we measure a value of $0.85 \pm 0.06$.
