Testing two alternatives theories to dark matter with the Milky Way dynamics

TL;DR

This study evaluates two alternative theories to dark matter—modified gravity and Bose-Einstein condensate halos—by testing their ability to explain the Milky Way's rotation curve and vertical acceleration, finding the collisionless fluid dark matter halo most consistent.

Contribution

It compares the effectiveness of modified gravity and Bose-Einstein condensate models against traditional dark matter halos in explaining Milky Way dynamics.

Findings

Modified gravity overestimates vertical acceleration.

Bose-Einstein condensate halos are barely consistent with observations.

Collisionless fluid dark matter best fits both rotation curve and vertical acceleration.

Abstract

Two alternative theories to dark matter are investigated by testing their ability to describe consistently the dynamics of the Milky Way. The first one refers to a modified gravity theory having a running gravitational constant and the second assumes that dark matter halos are constituted by a Bose-Einstein condensation. The parameters of each model as well as those characterizing the stellar subsystems of the Galaxy were estimated by fitting the rotation curve of the Milky Way. Then, using these parameters, the vertical acceleration profile at the solar position was computed and compared with observations. The modified gravity theory overestimates the vertical acceleration derived from stellar kinematics while predictions of the Bose-Einstein condensation halo model are barely consistent with observations. However, a dark matter halo based on a collisionless fluid satisfies our consistency test, being the best model able to describe equally well the rotation curve and the vertical acceleration of the Galaxy.