Testing modified Newtonian dynamics in the Milky Way

TL;DR

This paper tests modified Newtonian dynamics (MOND) against Milky Way data, finding that some versions of MOND can fit the galaxy's rotation curve, but future observations are needed to confirm its validity.

Contribution

It provides new constraints on MOND using recent Milky Way kinematic data and baryonic morphology, evaluating different interpolating functions and MOND-like theories.

Findings

The standard interpolating function cannot simultaneously fit Milky Way and external galaxy rotation curves.

The simple interpolating function can fit some baryonic models of the Milky Way.

Upcoming observations will further test the validity of MOND in the Galaxy.

Abstract

Modified Newtonian dynamics (MOND) is an empirical theory originally proposed to explain the rotation curves of spiral galaxies by modifying the gravitational acceleration, rather than by invoking dark matter. Here,we set constraints on MOND using an up-to-date compilation of kinematic tracers of the Milky Way and a comprehensive collection of morphologies of the baryonic component in the Galaxy. In particular, we find that the so-called "standard" interpolating function cannot explain at the same time the rotation curve of the Milky Way and that of external galaxies for any of the baryonic models studied, while the so-called "simple" interpolating function can for a subset of models. Upcoming astronomical observations will refine our knowledge on the morphology of baryons and will ultimately confirm or rule out the validity of MOND in the Milky Way. We also present constraints on MOND-like theories without making any assumptions on the interpolating function.