发表机构
Leiden Observatory, Leiden University（莱顿天文台，莱顿大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用IllustrisTNG模拟和1-DREAM框架，发现宇宙纤维内速度场的散度和涡度与暗物质晕质量及组装历史密切相关，动力学平静区域偏好大质量晕且组装更晚，为晕增长提供密度之外的补充描述。
AI 中文摘要
宇宙网通过各向异性的物质流控制着暗物质晕的增长，然而局部速度场动力学在晕质量组装中的作用仍知之甚少。速度场携带着物质输运的非线性信息，这些信息仅靠密度无法完全捕捉，尤其是在纤维结构内部。我们利用IllustrisTNG TNG50-1-Dark模拟中$z=0$时的暗物质晕，通过速度散度和涡度来研究这一联系。宇宙纤维采用1-DREAM框架提取，我们统计研究了在三种过密度区间内，晕质量与散度、涡度以及距纤维主轴径向距离的关系。速度场与宇宙网强烈相关，汇聚流追踪纤维，而涡度主要出现在过密、非线性区域。在纤维内部，散度和涡度在距主轴中等距离处均表现出增强的动力学活动，其幅度随过密度增加而增大。我们确认了明显的质量分层，即质量更大的晕优先位于纤维中心附近。最值得注意的是，质量$M \geq 10^{12} M_\odot$的晕几乎完全存在于低绝对散度和低涡度区域，而高动力学环境则由低质量晕主导。我们进一步发现，位于动力学平静区域的晕组装时间更晚，且比动力学活跃环境中的晕保持更高的近期吸积率，将当前速度场特性与晕增长历史联系起来。这些结果表明，宇宙流的局部动力学状态编码了超出密度单独所含的关于晕质量和组装的信息，为宇宙网内晕增长提供了互补的动力学描述。
英文摘要
The cosmic web governs the growth of dark matter halos through anisotropic matter flows, yet the role of local velocity-field dynamics in halo mass assembly remains poorly understood. The velocity field carries non-linear information about matter transport that is not fully captured by density alone, particularly within filaments. We investigate this connection through velocity divergence and vorticity using dark matter halos in the IllustrisTNG TNG50-1-Dark simulation at $z=0$. Cosmic filaments are extracted with the 1-DREAM framework, and we statistically study how halo mass relates to divergence, vorticity, and radial distance from filament spines across three overdensity regimes. The velocity field correlates strongly with the cosmic web, with converging flows tracing filaments and vorticity arising primarily in overdense, non-linear regions. Within filaments, both divergence and vorticity show enhanced kinematic activity at intermediate distances from the spine, with amplitudes increasing with overdensity. We confirm a clear mass segregation, with more massive halos preferentially located near filament centers. Most notably, halos with masses $M \geq 10^{12} M_\odot$ are found almost exclusively in regions of low absolute divergence and low vorticity, while highly dynamical environments are dominated by low-mass halos. We further find that halos residing in kinematically calm regions assembled later and maintain higher recent accretion rates than those in dynamically active environments, linking present-day velocity-field properties to halo growth histories. These results demonstrate that the local kinematic state of the cosmic flow encodes information about halo mass and assembly beyond that contained in density alone, providing a complementary dynamical description of halo growth within the cosmic web.
