On the curvature of dustlanes in galactic bars

TL;DR

This study confirms that stronger galactic bars tend to have straighter dust lanes, with the curvature primarily influenced by bar parameters, supported by observational data and simulations.

Contribution

It demonstrates that dust lane curvature correlates with bar strength and introduces a combined parameter (Qb and a/b) to better explain the spread in this relation.

Findings

Dust lane curvature inversely related to bar strength Qb.

Inclusion of a/b reduces spread in the curvature-Qb relation.

Bar parameters predominantly determine dust lane curvature.

Abstract

We test the theoretical prediction that the straightest dust lanes in bars are found in strongly barred galaxies, or more specifically, that the degree of curvature of the dust lanes is inversely proportional to the strength of the bar. The test used archival images of barred galaxies for which a reliable non-axisymmetric torque parameter (Qb) and the radius at which Qb has been measured (r(Qb)) have been published in the literature. Our results confirm the theoretical prediction but show a large spread that cannot be accounted for by measurement errors. We simulate 238 galaxies with different bar and bulge parameters in order to investigate the origin of the spread in the dust lane curvature versus Qb relation. From these simulations, we conclude that the spread is greatly reduced when describing the bar strength as a linear combination of the bar parameters Qb and the quotient of the major and minor axis of the bar, a/b. Thus we conclude that the dust lane curvature is predominantly determined by the parameters of the bar.