Galaxy merging in MOND

TL;DR

This study compares galaxy merging processes in MOND and Newtonian gravity with dark matter, revealing longer merging timescales in MOND but similar end-products, impacting observational interpretations.

Contribution

It provides the first detailed N-body simulation comparison of galaxy mergers in MOND versus Newtonian gravity with dark matter, highlighting differences in merging timescales.

Findings

Longer merging timescales in MOND than in Newtonian gravity with dark matter.

End-products of mergers are similar in MOND and Newtonian scenarios.

Observational evidence of rapid merging challenges MOND explanations.

Abstract

We present the results of N-body simulations of dissipationless galaxy merging in Modified Newtonian Dynamics (MOND). For comparison, we also studied Newtonian merging between galaxies embedded in dark matter halos, with internal dynamics equivalent to the MOND systems. We found that the merging timescales are significantly longer in MOND than in Newtonian gravity with dark matter, suggesting that observational evidence of rapid merging could be difficult to explain in MOND. However, when two galaxies eventually merge, the MOND merging end-product is hardly distinguishable from the final stellar distribution of an equivalent Newtonian merger with dark matter.