Dusty Winds: Extraplanar PAH Features of Nearby Galaxies
  Recent observations have shown the presence of dust and molecular material in
galactic winds, but relatively little is known about the distribution of these
outflow components. To shed some light on this issue, we have used IRAC images
from the Spitzer Space Telescope archive to investigate polycyclic aromatic
hydrocarbon (PAH) emission from a sample of 16 local galaxies with known winds.
Our focus on nearby sources (median distance 8.6 Mpc) has revealed detailed PAH
structure in the winds and allowed us to measure extraplanar PAH emission. We
have identified extraplanar PAH features on scales of ~ 0.8 - 6.0 kpc. We find
a nearly linear correlation between the amount of extraplanar PAH emission and
the total infrared flux, a proxy for star formation activity in the disk. Our
results also indicate a correlation between the height of extraplanar PAH
emission and star formation rate surface density, which supports the idea of a
surface density threshold on the energy or momentum injection rate for
producing detectable extraplanar wind material.
