利用Uchuu宇宙学模拟量化星系团的速度各向异性剖面
Quantifying the Velocity Anisotropy Profile of Galaxy Clusters Using the Uchuu Cosmological Simulation
AI总结：
基于Uchuu-UniverseMachine模拟，本研究全面分析了星系团的速度各向异性剖面beta(r)，发现其随半径、质量和红移呈现规律性演化，并推导了质量与关键物理半径的幂律标度关系，为解释星系团动力学演化提供了理论框架。
摘要：
星系团是研究宇宙结构形成和星系演化的强大实验室。我们使用Uchuu-UniverseMachine模拟星系目录，对星系团中的速度各向异性剖面beta(r)进行了全面分析，该目录结合了大体积Uchuu N-body模拟与UniverseMachine星系形成模型。我们重点关注log(M200) >= 13.9 [h^-1 M_sun]且红移最高至z = 1.5的星系团，研究了beta(r)作为星系团中心半径、质量和红移函数的行为。我们发现beta(r)呈现出普遍形状：在星系团核心附近从各向同性值上升，在约1.7 R200处达到峰值，由于轨道混合在3.4 R200附近下降，并由于首次落入星系的主导作用在外围区域再次增加。我们的结果表明，质量更大的星系团具有更高的径向各向异性和更大的峰值beta值。此外，beta(r)随红移演化，高红移星系团显示出更多径向主导的轨道和增强的落入运动。我们进一步推导了M200与关键物理半径之间依赖于红移的幂律标度关系：流体静力学半径(R_hs)、落入半径(R_inf)和 turnaround 半径(R_ta)。这些发现为解释观测星系团的动力学特性提供了稳健的理论框架，并为理解其动力学状态在宇宙时间内的演化提供了关键见解。
英文摘要：
Galaxy clusters are powerful laboratories for studying both cosmic structure formation and galaxy evolution. We present a comprehensive analysis of the velocity anisotropy profile, beta(r), in galaxy clusters using the Uchuu-UniverseMachine mock galaxy catalog, which combines the large-volume Uchuu N-body simulation with the UniverseMachine galaxy formation model. Focusing on clusters with log(M200) >= 13.9 [h^-1 M_sun] up to redshift z = 1.5, we investigate the behavior of beta(r) as a function of cluster-centric radius, mass, and redshift. We find that beta(r) exhibits a universal shape: it rises from isotropic values near the cluster core, peaks at approximately 1.7 R200, declines around 3.4 R200 due to orbital mixing, and increases again in the outskirts due to the dominance of first-infalling galaxies. Our results show that more massive clusters have higher radial anisotropy and larger peak beta values. Moreover, beta(r) evolves with redshift, with high-redshift clusters displaying more radially dominated orbits and enhanced infall motions. We further derive redshift-dependent power-law scaling relations between M200 and key physical radii: hydrostatic (R_hs), infall (R_inf), and turnaround (R_ta). These findings offer a robust theoretical framework for interpreting the dynamical properties of observed galaxy clusters and provide key insights into the evolution of their dynamical state over cosmic time.
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