A slow bar in the dwarf irregular galaxy NGC 3741

TL;DR

This paper measures the pattern speed of the HI bar in the gas-rich, dark matter-dominated galaxy NGC 3741, finding it to be a slow bar consistent with dynamical friction models.

Contribution

It provides the first measurement of the bar pattern speed in NGC 3741 using the Tremaine-Weinberg method, revealing a slow bar in a dark matter-dominated galaxy.

Findings

Pattern speed of 17.1 km/s/kpc with uncertainty

Ratio of co-rotation radius to bar length is 1.6

Supports models of slow bars caused by dynamical friction

Abstract

Using the Tremaine-Weinberg method, we measure the speed of the HI bar seen in the disk of NGC 3741. NGC 3741 is an extremely gas rich galaxy with an {H\,{\sc i}} disk which extends to about 8.3 times its Holmberg radius. It is also highly dark matter-dominated. Our calculated value of the pattern speed $\Omega_p$ is 17.1 $\pm$ 3.4 km $\textrm{s}^{-1}\textrm{kpc}^{-1}$. We also find the ratio of the co-rotation radius to the bar semi-major axis to be (1.6 $\pm$ 0.3), indicating a slow bar. This is consistent with bar models in which dynamical friction results in a slow bar in dark matter dominated galaxies.