Acceleration Relations in the Milky Way as Differentiators of Modified Gravity Theories

TL;DR

This paper evaluates how well modified gravity theories, specifically Weyl conformal gravity and MOND, explain the observed acceleration relations in the Milky Way, providing a test for alternative gravity models versus dark matter hypotheses.

Contribution

It extends previous work by applying recent Milky Way acceleration data to test the predictions of Weyl conformal gravity and MOND against observed acceleration relations.

Findings

Weyl conformal gravity and MOND can explain the Milky Way's acceleration data.

The study provides a comparative analysis of modified gravity theories versus dark matter models.

Results suggest certain modified gravity models are consistent with the observed acceleration relations.

Abstract

The dynamical mass of galaxies and the Newtonian acceleration generated from the baryons have been found to be strongly correlated. This correlation is known as 'Mass-Discrepancy Acceleration Relation' (MDAR). Further investigations have revealed a tighter relation - 'Radial Acceleration Relation' (RAR) - between the observed total acceleration and the (Newtonian) acceleration produced by the baryons. So far modified gravity theories have remained more successful than $\Lambda$CDM to explain these relations. However, a recent investigation has pointed out that, when RAR is expressed as a difference between the observed acceleration and the expected Newtonian acceleration due to baryons (which has been called the 'Halo acceleration relation or HAR'), it provides a stronger test for modified gravity theories and dark matter hypothesis. Extending our previous work \citep{kt2018}, we present a case study of modified gravity theories, in particular Weyl conformal gravity and Modified Newtonian Dynamics (MOND), using recent inferred acceleration data for the Milky Way. We investigate how well these theories of gravity and the RAR scaling law can explain the current observation.