Milky Way dark matter distribution or MOND test from vertical stellar kinematics with Gaia DR3

TL;DR

This study uses Gaia DR3 data to analyze the vertical stellar kinematics in the Milky Way, testing dark matter models and MOND, and finds that visible matter alone can explain the observations within uncertainties.

Contribution

It provides a comprehensive analysis of the Milky Way's mass distribution using Gaia DR3 data, challenging the necessity of dark matter or MOND in certain regions.

Findings

Spherical dark matter halos and MOND are compatible with data.

Disky dark matter model is excluded by the data.

No significant dark matter detected within Newtonian gravity in the studied regions.

Abstract

Vertical stellar kinematics+density can be used to trace the dark matter distribution [or the equivalent phantom mass in a Modified Newtonian Dynamics (MOND) scenario] through Jeans equations. In this paper, we want to improve this type of analysis by making use of the recent data of the 6D information from the Gaia-DR3 survey in the anticenter and the Galactic poles to obtain the dynamical mass distribution near plane regions, including extended kinematics over a wide region of 8 kpc$<R<$22 kpc, $|z|<3$ kpc. Our conclusions are as follows: (i) the model of the spherical dark matter halos and the MOND model are compatible with the data; (ii) the model of the disky dark matter (with density proportional to the gas density) is excluded; (iii) the total lack of dark matter (there is only visible matter) within Newtonian gravity is compatible with the data; for instance, at solar Galactocentric radius, we obtained $\Sigma=39\pm 18$ M$_\odot$ pc$^{-2}$ for $z=1.05$ kpc, compatible with the expected value for visible matter alone of 44 M$_\odot$ pc$^{-2}$, thus allowing zero dark matter. Similarly, for $R>R_\odot$, $z=1.05$ kpc: $\Sigma=28.7\pm 9.6$, $23.0\pm 5.7$, $16.9\pm 5.8$, $11.4\pm 6.6$ M$_\odot$ pc$^{-2}$, respectively, for $R=10,13,16,19$ kpc, compatible with visible matter alone. Larger error bars in comparison with previous works are not due to worse data or a more awkward technique but to a stricter modeling of the stellar distribution.