The Passage of Light within Spiral Galaxies

Galaxies seen edge-on offer an unique perspective on the structure of both stars and interstellar matter. How stellar light travels through a spiral galaxy is affected by the interstellar matter; interstellar dust absorbs starlight and re-emits the energy in far-infrared. In the edge-on case, the absorption often manifests itself in the form of dark dustlanes in optical images.

How the stellar light is transported through the disk and affected by the dusty interstellar medium can be modeled using radiative transport models such as TRADING, DIRTY, SKIRT and many more. The current models are set to converge on a self-consistent model for the many of the edge-on galaxies for which multi-wavelength data now exists (Ultra-violet to sub-millimeter observations).

The aim of the workshop is to convene the authors and users of radiative transport models for edge-on spiral galaxies and set up an exhaustive comparison to the existing multi wavelength imaging data and observational constraints. Thus, we can, in time, collectively identify galaxy properties for the full sample of edge-on spirals and single out points for improvement in the data and models.

Workshop Questions:

Which additional data is needed to break the degeneracy of edge-on SED models? Far-infrared imaging? HST mapping of extinction or IFU observations? More sub-millimeter imaging with SCUBA or ALMA? Is more data on few systems even the correct approach?

What model refinements are needed? (more stellar populations? improved grain absorption models? ISM geometries?) What boundary conditions can we use? (e.g. power spectra of nearby face-on galaxies or dust maps from occulting galaxy pairs?).

What are the next science questions to be answered with the new crop of data and models? Is there a phase-change with mass in the vertical structure of galaxies? How clumped does the ISM need to be? Is there an “Energy Budget Crisis”? Are dust lanes a long-lasting phenomenon?