The frequency of dust lanes in edge-on spiral galaxies identified by Galaxy Zoo in KiDS imaging of GAMA targets

TL;DR

This study uses Galaxy Zoo classifications on KiDS imaging to analyze how dust lanes in edge-on spiral galaxies relate to galaxy properties like stellar mass, bulge shape, and dust content, revealing their dependence on mass and bulge morphology.

Contribution

It provides new insights into the relation between dust lane occurrence and galaxy characteristics, especially stellar mass and bulge morphology, based on large-scale morphological classification.

Findings

Dust lanes appear at stellar masses above ~10^9 M_sun.

Presence of dust lanes correlates with bulge roundness.

Dust lanes are linked to a mix of cold dust components along the line of sight.

Abstract

Dust lanes bisect the plane of a typical edge-on spiral galaxy as a dark optical absorption feature. Their appearance is linked to the gravitational stability of spiral disks; the fraction of edge-on galaxies that displays a dust lane is a direct indicator of the typical vertical balance between gravity and turbulence; a balance struck between the energy input from star-formation and the gravitational pull into the plane of the disk. Based on morphological classifications by the Galaxy~Zoo project on the Kilo-Degree Survey (KiDS) imaging data in the Galaxy and Mass Assembly (GAMA) fields, we explore the relation of dust lanes to the galaxy characteristics, most of which were determined using the {\sc magphys} spectral energy distribution fitting tool: stellar mass, total and specific star-formation rates, and several parameters describing the cold dust component. We find that the fraction of dust lanes does depend on the stellar mass of the galaxy; they start to appear at $M^* \sim 10^9 M_\odot$. A dust lane also implies strongly a dust mass of at least $10^5 M_\odot$, but otherwise does not correlate with cold dust mass parameters of the {\sc magphys} spectral energy distribution analysis, nor is there a link with star-formation rate, specific or total. Dust lane identification does not depend on disk ellipticity (disk thickness) or Sersic profile but correlates with bulge morphology; a round bulge favors dust lane votes. The central component along the line of sight that produces the dust lane is not associated with either one of the components fit by {\sc magphys}, the cold diffuse component or the localized, heated component in HII regions, but a mix of these two.