银河系旋转曲线的自洽金斯分析
A Self-Consistent Jeans Analysis of the Milky Way Rotation Curve
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- Tsinghua University（清华大学）
- LIRA, Observatoire de Paris, Université PSL, CNRS（巴黎天文台 LIRA 实验室，巴黎大学，法国国家科学研究中心）
- Center for Astronomy, Space Science and Astrophysics, Independent University, Bangladesh（孟加拉独立大学天体物理学、空间科学与天文学中心）
- Local Universe and Time-Domain Astronomy Laboratory, Department of Astronomy, China West Normal University（西华师范大学天文学院本地宇宙与时域天文实验室）
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中文总结 AI 辅助
通过自洽的金斯分析，利用运动学均匀的示踪体样本，重新评估银河系外盘旋转曲线，发现其仍呈开普勒式下降，并给出动力学质量约2.01×10^11太阳质量。
中文摘要 AI 辅助
基于金斯方程的银河系（MW）旋转曲线（RC）测量揭示了外盘旋转曲线的下降趋势。然而，其解释在很大程度上依赖于示踪体的选择、示踪体密度轮廓、金斯方程中的梯度项以及外盘中的非轴对称扰动。我们提出了一种更为自洽的银河系旋转曲线金斯分析，并在对主要金斯项及其相关系统不确定性（包括与非轴对称扰动相关的不确定性）进行修正处理后，重新评估外盘下降趋势是否仍然存在。我们选取了一个运动学上均匀的盘示踪体样本，旨在保留近似圆轨道上的恒星，仅移除了原始样本的12%。我们使用与运动学矩相同的恒星来估计示踪体密度轮廓，而非采用外部尺度长度。我们发现，在验证范围12.5 < R < 21 kpc内，示踪体密度轮廓更好地由双指数函数描述。我们还评估了与基准金斯方程项相关的主要系统不确定性，包括常被忽略的交叉项，并考虑了外盘子结构中不同的旋转速度。推导出的旋转曲线在内盘保持近似平坦，在大半径处下降。在采用的外区间$R\trsim16\\,\mathrm{kpc}$内，即使考虑了系统不确定性，旋转曲线斜率也与开普勒下降一致。相应的质量建模给出了外推动力学质量为$2.01^{+0.10}_{-0.08}\times10^{11}\\,M_\odot$。
英文摘要
Jeans-based measurements of the Milky Way (MW) rotation curve (RC) have revealed a declining outer RC. The interpretation, however, depends sensitively on the tracer selection, the tracer density profile, gradient terms in the Jeans equation, and non-axisymmetric perturbations in the outer disk. We present a more self-consistent Jeans analysis of the MW RC and reassess whether the outer decline remains after a revised treatment of the main Jeans terms and their associated systematic uncertainties, including those related to non-axisymmetric perturbations. We select a kinematically homogeneous disk tracer sample designed to retain stars on nearly circular disk orbits, removing only 12\% of the original sample. We estimate the tracer density profile from the same stars used for the kinematic moments, rather than adopting an external scale length. We find that the tracer density profile is better described by a double exponential over the validated range 12.5 < R < 21 kpc. We also assess the main systematic uncertainties associated with the fiducial Jeans equation terms, including the often neglected cross term, and account for different rotational velocities in the outer disk substructures. The derived RC remains nearly flat in the inner disk and declines at large radii. Over the adopted outer interval, $R\gtrsim16\,\mathrm{kpc}$, the RC slope is consistent with a Keplerian decline even after accounting for the systematic uncertainties. The corresponding mass modeling gives an extrapolated dynamical mass of $2.01^{+0.10}_{-0.08}\times10^{11}\,M_\odot$.
