Theoretical implications of the galactic radial acceleration relation of McGaugh, Lelli, and Schombert

TL;DR

This paper explores the galactic radial acceleration relation, showing that LCDM, conformal gravity, and MOND can all produce similar universal acceleration functions, with potential to distinguish between models using precise rotation data.

Contribution

It demonstrates that LCDM and conformal gravity can also produce the observed universal acceleration relation, challenging the notion that it uniquely supports MOND.

Findings

All three models can produce the universal acceleration correlation.

LCDM requires specific dark matter distributions.

Conformal gravity predicts a mass-independent acceleration function.

Abstract

Velocities in stable circular orbits about galaxies, a measure of centripetal gravitation, exceed the expected Kepler/Newton velocity as orbital radius increases. Standard LCDM attributes this anomaly to galactic dark matter. McGaugh et al have recently shown for 153 disc galaxies that observed radial acceleration is an apparently universal function of classical acceleration computed for observed galactic baryonic mass density. This is consistent with the empirical MOND model, not requiring dark matter. It is shown here that suitably constrained LCDM and conformal gravity (CG) also produce such a universal correlation function. LCDM requires a very specific dark matter distribution, while the implied CG nonclassical acceleration must be independent of galactic mass. All three constrained radial acceleration functions agree with the empirical baryonic $v^4$ Tully-Fisher relation. Accurate rotation data in the nominally flat velocity range could distinguish between MOND, LCDM, and conformal gravity.