AI 中文总结
本研究结合SDSS DR12星系样本与Bisous纤维目录，发现卫星轨道平面取向与宇宙纤维存在12.8σ显著性的关联，为纤维吸积两阶段模型提供了直接观测证据。
AI 中文摘要
我们开展了一项关于卫星轨道平面与宇宙网之间运动学相干性的观测研究。结合SDSS DR12星系样本与Bisous纤维目录，我们探究卫星的轨道运动是否保留了纤维吸积的记忆。对每个卫星系统，我们利用星系天球位置与视线速度偏移量定义了一个投影轨道法向量。通过测量该向量与局域投影纤维方向之间的夹角θ，我们探测到了一种独特的偏好取向：卫星轨道平面倾向于包含纤维轴或与纤维轴平行。该信号以12.8σ的高显著性水平偏离各向同性预期。这种运动学关联的强度强烈依赖于环境与宿主属性：在靠近纤维脊线的星系群中以及质量更大的宿主处，轨道平面追踪纤维方向的偏好最为显著；相反，在距纤维中等距离处以及星系群中心大半径处，该信号发生反转，表明轨道平面倾向于垂直于纤维。我们的发现为纤维吸积的两阶段模型提供了直接观测证据，该模型中从初始向纤维脊线的垂直坍缩到后续沿纤维方向流入暗物质晕的平行下落的转变，决定了卫星轨道角动量与星系自旋的取向。观测到的转变还可能进一步追踪纤维的特征径向尺度，为宇宙纤维的内部结构与形成组装提供了动力学视角。
英文摘要
We present an observational study of the kinematic coherence between satellite orbital planes and the cosmic web. Using the SDSS DR12 galaxy sample combined with the Bisous filament catalogue, we investigate whether the orbital motion of satellites preserves the memory of filamentary accretion. For each satellite system, we define a projected orbital-normal vector using galaxy sky positions and line-of-sight velocity offsets. By measuring the angle $θ$ between this vector and the local projected filament direction, we detect a distinctive preferred orientation: satellite orbital planes tend to contain or lie parallel to the filament axis. This signal deviates from the isotropic expectation at a high significance level of $12.8σ$. The strength of this kinematic connection depend strongly on environment and host properties. The preference for orbital planes to track the filament direction is most pronounced for groups in close distance to the filament spine and for more massive hosts. Conversely, at intermediate distances from the filament and at large group-centric radii, the signal reverses, indicating a tendency for orbital planes to be oriented perpendicular to the filament. Our findings provide direct observational evidence for the two-phase model of filamentary accretion, where a transition from initial perpendicular collapse toward the filament spine to subsequent parallel streamwise infall into dark matter haloes governs the orientation of satellite orbital angular momentum and galaxy spin. The observed transition may further trace the characteristic radial scale of filaments, offering a dynamical perspective on the internal structure and assembly of the cosmic filament.
Comments11 pages,4 figures, accepted by ApJL
