The Dust Lane in Edge-On Spiral Galaxies.

Part of the edge-on perspective of a spiral galaxy is the thin dark band due to interstellar dust absorption. The cumulative effect of interstellar matter clouds in the disk dim the stellar light enough to result in the dark band mid-plane. The presence and characteristics of this morphological feature are telling of the underlying physics of the disk itself. The canonical view is that in massive disks, the vertical balance between gravitational pull and turbulence in the ISM results in a thin dust lane while in less massive galaxies the dust clouds are distributed throughout the height of the stellar disk. However, this result was based on a select sample of bulgeless galaxies and a dust lane can only be identified reliably if the stellar disk is thick enough to highlight it.

With the launch of the Herschel Space Observatory, it is now possible to resolve the height of the dust disk in nearby spirals. Several massive edge-on spirals are targeted by legacy programs, specifically by the HEROES project and I present my complementary survey of low-mass edge-on spirals, NHEMESES. The first result was on NGC 4244 with 13 more galaxies slated to be observed. Complementary to these far-infrared and sub-mm observations, a survey of dust lanes in SDSS by the GalaxyZOO2 citizen science project sheds more light on dust lane frequency in local edge-on spirals. And in the HST COSMOS imaging, the communality of dust lanes in massive edge-on spirals can be explored to higher redshift (z~1). I present the first results from both these projects.