On the morphology of dust lanes in galactic bars

TL;DR

This study uses dynamical simulations and a new measurement method to analyze how bar strength and pattern speed influence dust lane shapes in galactic bars, revealing different behaviors for fast and slow bars.

Contribution

It introduces a novel systematic method for measuring dust lane curvature and extends the analysis to slow bars, providing new insights into their dust lane morphology.

Findings

Inverse relation between dust lane curvature and bar strength in fast bars.

Constant dust lane curvature across bar strengths in slow bars.

Observed dust lane curvatures consistent with simulation predictions.

Abstract

The aim of our study is to use dynamical simulations to explore the influence of two important dynamical bar parameters, bar strength and bar pattern speed, on the shape of the bar dust lanes. To quantify the shape of the dust lanes we have developed a new systematic method to measure the dust lane curvature. Previous numerical simulations have compared the curvature of bar dust lanes with the bar strength, predicting a relation between both parameters which has been supported by observational studies but with a large spread. We take into account the bar pattern speed to explore, simultaneously, the effect of both parameters on the dust lane shape. To that end, we separate our galactic bars in fast bars $\left(1 < \mathcal{R} < 1.4 \right)$ and slow bars $\left(\mathcal{R} > 1.4 \right)$, obtaining, as previous simulations, an inverse relation between the dust lane curvature and the bar strength for fast bars. For the first time, we extend the study to slow bars, finding a constant curvature as a function of the bar strength. As a result, we conclude that weak bars with straight dust lanes are candidates for slow bars. Finally, we have analysed a pilot sample of ten S$^4$G galaxies, obtaining dust lane curvatures lying within the range covered by the simulations.