On the Evidence for Violation of the Equivalence Principle in Disk Galaxies

TL;DR

This paper critically re-examines claims of an external field effect in disk galaxies, arguing that observed correlations can be explained without violating Einstein's equivalence principle, challenging previous interpretations.

Contribution

It offers an alternative interpretation of galaxy observations that does not require the external field effect, questioning prior claims of its detection.

Findings

Observed galaxy correlations can be explained without EFE

Re-analysis does not confirm the presence of EFE

Challenges previous claims of EFE detection in galaxies

Abstract

We examine the claimed observations of a gravitational external field effect (EFE) reported in Chae et al. We show that observations suggestive of the EFE can be interpreted without violating Einstein's equivalence principle, namely from known correlations between morphology, environment and dynamics of galaxies. While Chae et al's analysis provides a valuable attempt at a clear test of Modified Newtonian Dynamics, an evidently important topic, a re-analysis of the observational data does not permit us to confidently assess the presence of an EFE or to distinguish this interpretation from that proposed in this article.