The Redshift-Dependence of Radial Acceleration: Modified Gravity versus Particle Dark Matter

TL;DR

This paper compares modified gravity theories and particle dark matter in explaining galactic rotation curves, showing that a covariant emergent gravity model can fit data without free parameters and proposing redshift dependence as a distinguishing test.

Contribution

It demonstrates that a covariant version of Verlinde's emergent gravity eliminates the need for an interpolation function and fixes its free parameter, providing a better fit to rotation curve data.

Findings

The covariant emergent gravity model fits rotation curve data without free parameters.

Redshift dependence of rotation curves can differentiate between modified gravity and dark matter.

The model aligns well with observed acceleration correlations in galaxies.

Abstract

Modified Newtonian Dynamics has one free parameter and requires an interpolation function to recover the normal Newtonian limit. We here show that this interpolation function is unnecessary in a recently proposed covariant completion of Erik Verlinde's emergent gravity, and that Verlinde's approach moreover fixes the function's one free parameter. The so-derived correlation between the observed acceleration (inferred from rotation curves) and the gravitational acceleration due to merely the baryonic matter fits well with data. We then argue that the redshift-dependence of galactic rotation curves could offer a way to tell apart different versions of modified gravity from particle dark matter.