# Are Over-massive Haloes of Ultra Diffuse Galaxies Consistent with Extended MOND?

## TL;DR

This study tests whether Extended Modified Newtonian Dynamics (EMOND) can explain the large apparent dark matter effects in ultra-diffuse galaxies within the Coma cluster, by modeling their dynamics and comparing predictions.

## Contribution

It applies EMOND to model UDGs in the Coma cluster and assesses its ability to account for their observed masses, linking galaxy dynamics with the fundamental manifold.

## Key findings

- EMOND can explain UDG masses if they follow the fundamental manifold.
- One UDG deviates from the fundamental manifold, indicating the need for more data.
- Modeling errors are within expected ranges.

## Abstract

A sample of Coma cluster ultra-diffuse galaxies (UDGs) are modelled in the context of Extended Modified Newtonian Dynamics (EMOND) with the aim to explain the large dark matter-like effect observed in these cluster galaxies. We first build a model of the Coma cluster in the context of EMOND using gas and galaxy mass profiles from the literature. Then assuming the dynamical mass of the UDGs satisfies the fundamental manifold of other ellipticals, and that the UDG stellar mass-to-light matches their colour, we can verify the EMOND formulation by comparing two predictions of the baryonic mass of UDGs. We find that EMOND can explain the UDG mass, within the expected modelling errors, if they lie on the fundamental manifold of ellipsoids, however, given that measurements show one UDG lying off the fundamental manifold, observations of more UDGs are needed to confirm this assumption.