发表机构
Institute for Astronomy, University of Edinburgh; Royal Observatory, Blackford Hill, Edinburgh; Institute of Corpuscular Physics (IFIC), CSIC–Universitat de València; Space Telescope Science Institute; Center for Astrophysical Sciences, The William H. Miller III Department of Physics & Astronomy, Johns Hopkins University; McWilliams centre for Cosmology and Astrophysics, Department of Physics, Carnegie Mellon University（爱丁堡大学天文研究所; 皇家天文台; 粒子物理研究所（IFIC），西班牙国家研究委员会-巴伦西亚大学; 太空望远镜科学研究所; 约翰霍普金斯大学天体物理学中心威廉H米勒三世物理与天文学系; 卡内基梅隆大学物理学院麦克休斯宇宙学与天体物理中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过N体模拟发现暗物质次晕遭遇会在矮球状星系中产生瞬态、局部的旋转样运动学特征，其功率谱可量化空间尺度，为探测暗物质次结构提供群体级诊断工具。
AI 中文摘要
我们使用受控的N体模拟来研究暗物质次晕是否会在矮球状星系的内部运动学中留下可探测的特征。在每个快照中，我们将速度分布函数拟合到恒星的视线速度和自行，构建投影速度分量的归一化残差场，并分析其功率谱。我们表明，次晕遭遇会产生多种运动学特征。其中最突出的是类似旋转的信号，即使恒星成分在初始化时没有固有旋转，这些信号也会在我们的模型中出现。仅从视线速度来看，几个快照类似于与静止旋转相关的经典蓝移-红移模式。然而，天空平面分量带来了复杂性，交替出现膨胀和收缩区域，以及顺时针和逆时针流动。尽管我们在全局观察到连贯的流动，但这些结构偏离了典型的平衡配置，而其残差功率谱量化了所涉及的特征空间尺度。在包含更大质量次晕的模型中，这种信号会增强，而对于较小的恒星样本则难以恢复：完整速度空间特征的稳健功率谱恢复通常需要O(10^{4})个示踪体，尽管仅旋转信号可以用相当小的样本恢复。这些结果表明，矮球状星系的速度场可以保留次晕加热的特征。未来的光谱观测、改进的盖亚天体测量和化学动力学信息应将这一诊断转化为暗物质次结构的群体级探针。
英文摘要
We use controlled N-body simulations to investigate whether dark matter subhaloes leave detectable signatures in the internal kinematics of dwarf spheroidal galaxies. At each snapshot, we fit a velocity distribution function to stellar line-of-sight velocities and proper motions, construct normalised residual fields for the projected velocity components, and analyse their power-spectra. We show that subhalo encounters generate a plethora of kinematic features. Amongst the most prominent are rotation-like signals, which arise in our models even though the stellar component is initialised without intrinsic rotation. In line-of-sight velocity alone, several snapshots resemble the classical blueshift--redshift pattern associated with stationary rotation. The plane-of-sky components, however, bring complexity, with alternating regions of expansion and contraction, as well as clockwise and anticlockwise streaming. Although we observe coherent streaming globally, these structures depart from typical equilibrium configurations, while their residual power-spectra quantify the characteristic spatial scales involved. This signal strengthens in models containing more massive subhaloes and becomes difficult to recover for small stellar samples: robust power-spectrum recovery of the full velocity-space signature usually requires O(10^{4}) tracers, although a rotation signal alone can be recovered with considerably smaller samples. These results suggest that dwarf spheroidal velocity fields can retain signatures of subhalo heating. Future spectroscopy, improved Gaia astrometry, and chemo-dynamical information should turn these diagnostics into population-level probes of dark matter substructure.
Comments24 pages, 11 figures. Submitted. Comments are welcome
