A Self-consistent Jeans Analysis of the Milky Way Rotation Curve
Abstract
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 nonaxisymmetric 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 nonaxisymmetric 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 ≳ 16 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 2.0 1 − 0.08 + 0.10 × 1 0 11 M ⊙ .
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BibTeX
@article{jiao2026selfconsistent,
title = {{A Self-consistent Jeans Analysis of the Milky Way Rotation Curve}},
author = {Yongjun Jiao and 永俊 焦 and Francois Hammer and Istiak Akib and Yanbin Yang and 雁宾 杨 and Haifeng Wang and 海峰 王},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/aeaa43},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeaa43},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Self-consistent Jeans Analysis of the Milky Way Rotation Curve
AU - Yongjun Jiao
AU - 永俊 焦
AU - Francois Hammer
AU - Istiak Akib
AU - Yanbin Yang
AU - 雁宾 杨
AU - Haifeng Wang
AU - 海峰 王
PY - 2026
DA - 2026/11/05
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeaa43
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeaa43
AB - 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 nonaxisymmetric 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 nonaxisymmetric 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 ≳ 16 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 2.0 1 − 0.08 + 0.10 × 1 0 11 M ⊙ .
SN - 1538-4357
SN - 0004-637X
ER -