| Description |
We propose deep PACS and SPIRE imaging for all (6) normal, edge-on (i >85 deg) galaxies with d<10Mpc as part of the Herschel EDGEon galaxy Survey (HEDGES). These data will allow us, for the first time, to characterize variations in the far-infrared (FIR) spectral energy distribution (SED) among and within halos for an energetically diverse sample of nearby, edge-on galaxies as a function of height above the disk. The proper sampling of the halo dust SEDs (i.e., 6 bands between 70500um), will allow us to take inventory of the dust content of halos and illuminate the signatures of dust processing imprinted in the dust SED and its variations. These observations will provide a way to address a number of outstanding questions related to the processes governing the interchange of disk/halo material such as: (1) How does halo dust content relate to disk star formation activity? (2) What are the physical characteristics of halo dust (i.e., temperature(s), mass, emissivity, PAH mass fraction, and what does their variation with height from the plane tell us about grain modification by the energetic processes responsible for disk-halo cycling? (3) What can dust and radio continuum halos tell us about transport effects that are important for understanding the FIR-Radio correlation? (4) How does the distribution of halo dust compare to that of other gas tracers, and hence what can we learn about how such dust is associated with various gas phases? The HEDGES sample galaxies have a treasury of ancillary data (e.g., radio, Spitzer, optical, gas), and the addition of these deep Herschel data will make HEDGES the definitive sample to study multi-phase disk/halo feedback processes arising from the accretion, expulsion, and/or cycling of material between disks and halos into the foreseeable future. |
