AI 中文总结
该研究利用 SAMI 星系和 NewHorizon 模拟数据，通过施瓦兹席尔德轨道叠加等方法，重新审视盘状恒星质量与速度弥散关系并扩展到薄厚盘，揭示了相关结果及系统误差，为未来研究盘状子结构提供方向。
AI 中文摘要
我们重新审视盘状恒星质量与盘速度弥散（M_* - \sigma_e）之间的关系，并使用 161 个 SAMI 星系的基于轨道的动力学模型以及 NewHorizon 模拟中 31 个盘状星系的对应测量值，将其扩展到薄盘和厚盘子成分。在观测方面，应用施瓦兹席尔德轨道叠加来恢复轨道圆度分布和成分运动学。在模拟方面，按圆度以及分别按恒星年龄对薄盘和厚盘进行采样以测试分类依赖性。分析揭示三个主要结果：盘遵循紧密的 M_* - \sigma_e 关系，几乎与球状星团关系平行；对于基于圆度和年龄的定义，厚盘成分系统地比薄盘成分热，且薄厚弥散比仅随质量微弱变化；存在方法和数据系统误差。这些结果与垂直平衡标度设定的基线一致，长期加热随时间积累并调节固定质量下的弥散。未来化学动力学建模和更高分辨率、化学追踪模拟的测试将对外部星系中的盘状子结构提供更强约束。
英文摘要
We revisit the relation between disc stellar mass and disc velocity dispersion (M_*-σ_e) and extend it to thin and thick subcomponents using orbit-based dynamical models of 161 SAMI galaxies and counterpart measurements for 31 disc galaxies in the NewHorizon simulation. On the observational side, we apply Schwarzschild orbit superposition to recover orbital circularity distributions and component kinematics. On the simulation side, we sample thin and thick discs by circularity and, separately, by stellar age to test classification dependence. Our analysis reveals three main results. (1) Discs follow a tight M_*-σ_e relation, nearly parallel to the bulge relation. (2) For both circularity- and age-based definitions, the thick-disc component is systematically hotter than the thin-disc component, and the thin-thick dispersion ratio varies only weakly with mass. However, age cuts yield a smaller kinematic contrast, indicating that stellar age and orbital circularity do not map one-to-one and that no single global age threshold reproduces the circularity-based split. (3) Method and data systematics are present, with Schwarzschild modelling returning slightly higher disc σ_e than spectroscopic bulge-disc decompositions, and simulated discs showing lower σ_e at fixed mass than observed. All these results are consistent with a baseline set by vertical-equilibrium scalings, with secular heating accumulating over time and modulating the dispersion at fixed mass. Occasional minor interactions may add localised heating but do not appear to be essential for explaining the qualitative, global trends reported here. Future tests with chemo-dynamical modelling and higher-resolution, chemistry-tracking simulations will provide stronger constraints on disc substructures in external galaxies.
Comments14 pages, 9 figures
