Testing modified gravity theory in the Milky Way

Abstract

We perform a test of John Moffat's modified gravity theory (MOG) within the Milky Way, adopting the well-known "rotation curve" method. We use the dynamics of observed tracers within the disk to determine the gravitational potential as a function of galactocentric distance and compare that with the potential that is expected to be generated by the visible component only (stars and gas) under different "flavors" of the MOG theory, making use of a state-of-the-art setup for both the observed tracers and baryonic morphology. Our analysis shows that in both the original and the modified version (considering a self-consistent evaluation of the Milky Way mass), the theory fails to reproduce the observed rotation curve. We conclude that in none of its present formulations is the MOG theory able to explain the observed rotation curve of the Milky Way.