Are Dwarf Galaxies Dominated by Dark Matter?

TL;DR

This study shows that the stellar disks in late-type dwarf galaxies can often explain their rotation curves without requiring dominant dark matter, challenging the notion that such galaxies are primarily dark matter dominated.

Contribution

It demonstrates that maximum disk models can successfully fit rotation curves of dwarf galaxies, indicating a close coupling between luminous and total mass distributions.

Findings

Maximum disk models fit most dwarf galaxy rotation curves.

High mass-to-light ratios are needed in some cases.

Inner rotation curves are well explained by stellar mass distribution.

Abstract

Mass models for a sample of 18 late-type dwarf and low surface brightness galaxies show that in almost all cases the contribution of the stellar disks to the rotation curves can be scaled to explain most of the observed rotation curves out to two or three disk scale lengths. The concept of a maximum disk, therefore, appears to work as well for these late-type dwarf galaxies as it does for spiral galaxies. Some of the mass-to-light ratios required in our maximum disk fits are high, however, up to about 15 in the R-band, with the highest values occurring in galaxies with the lowest surface brightnesses. Equally well-fitting mass models can be obtained with much lower mass-to-light ratios. Regardless of the actual contribution of the stellar disk, the fact that the maximum disk can explain the inner parts of the observed rotation curves highlights the similarity in shapes of the rotation curve of the stellar disk and the observed rotation curve. This similarity implies that the distribution of the total mass density is closely coupled to that of the luminous mass density in the inner parts of late-type dwarf galaxies.