Milky Way Dynamics Favor Dark Matter over Modified Gravity Models
Abstract
Modified gravity theories such as Modified Newtonian Dynamics (MOND) and Scalar-Tensor-Vector Gravity (STVG) have been proposed as alternatives to dark matter, but decisive tests have been hindered by degeneracies between baryonic structure and gravitational laws. Here we break this degeneracy using independent, high-precision constraints: the Milky Way radial rotation curve, vertical phase-space spirals from Gaia, and a broken-exponential stellar disk. A joint reconstruction of the radial and vertical gravitational fields reveals a structural inconsistency in modified gravity -- no model can simultaneously reproduce both observations. Our results strongly disfavor MOND at and STVG at . In contrast, dark matter halo models naturally explain the observations, providing a self-consistent test of gravity on galactic scales.
Keywords
Cite
@article{arxiv.2605.10857,
title = {Milky Way Dynamics Favor Dark Matter over Modified Gravity Models},
author = {Zheng-long Wang and Yue-Lin Sming Tsai and Lan Zhang and Yin Wu and Haining Li and Xiang-Xiang Xue and Hongsheng Zhao and Yi-Zhong Fan},
journal= {arXiv preprint arXiv:2605.10857},
year = {2026}
}