Interacting Galaxies with MOND

TL;DR

This study compares galaxy interactions in MOND and Newtonian gravity with dark matter, showing MOND predicts faster bar formation and longer merger times, aligning better with observations.

Contribution

Developed a grid-based adaptive mesh refinement code to compare galaxy dynamics in MOND and Newtonian gravity, highlighting differences in bar formation and merger times.

Findings

Galaxies in MOND form bars faster and stronger.

Merger time-scales are longer in MOND due to weaker dynamical friction.

MOND better reproduces observed high frequency of strong bars.

Abstract

We compare N-body simulations performed in MOND with analogs in Newtonian gravity with dark matter (DM). We have developed a code which solves the Poisson equation in both gravity models. It is a grid solver using adaptive mesh refinement techniques, allowing us to study isolated galaxies as well as interacting galaxies. Galaxies in MOND are found to form bars faster and stronger than in the DM model. In Newton dynamics, it is difficult to reproduce the observed high frequency of strong bars, while MOND appears to fit better the observations. Galaxy interactions and mergers, such as the Antennae, are also simulated with Newton and MOND dynamics. In the latter, dynamical friction is much weaker, and merging time-scales are longer. The formation of tidal dwarf galaxies in tidal tails are also compared in MOND and Newton+DM models.