Loss of mass and stability of galaxies in MOND

TL;DR

This paper explores how MOND-based gravity predicts galaxy stability and mass loss depend on environmental acceleration, suggesting observable effects like Keplerian orbits and galaxy instability in clusters, challenging conventional dark matter models.

Contribution

It introduces the idea that MOND gravity effects vary with environment, affecting galaxy stability and dynamics, and proposes observable tests to falsify these predictions.

Findings

Galaxy stability decreases with higher acceleration in MOND

Satellites in field galaxies follow nearly Keplerian orbits at large radii

Galaxies in clusters are predicted to be unstable without dark halos

Abstract

The self-binding energy and stability of a galaxy in MOND-based gravity are curiously decreasing functions of its center of mass acceleration towards neighbouring mass concentrations. A tentative indication of this breaking of the Strong Equivalence Principle in field galaxies is the RAVE-observed escape speed in the Milky Way. Another consequence is that satellites of field galaxies will move on nearly Keplerian orbits at large radii (100 - 500 kpc), with a declining speed below the asymptotically constant naive MOND prediction. But consequences of an environment-sensitive gravity are even more severe in clusters, where member galaxies accelerate fast: no more Dark-Halo-like potential is present to support galaxies, meaning that extended axisymmetric disks of gas and stars are likely unstable. These predicted reappearance of asymptotic Keplerian velocity curves and disappearance of "stereotypic galaxies" in clusters are falsifiable with targeted surveys.