Temperature Variations of the Cold Dust in the Triangulum Galaxy M33
  We present wide-field 1.1 mm continuum imaging of the nearby spiral galaxy M
33, conducted with the AzTEC bolometer camera on ASTE. We show that the 1.1 mm
flux traces the distribution of dust with T ~20 K. Combined with far-infrared
imaging at 160um, we derive the dust temperature distribution out to a galactic
radius of ~7 kpc with a spatial resolution of ~100 parsecs. Although the 1.1 mm
flux is observed predominantly near star forming regions, we find a smooth
radial temperature gradient declining from ~20 K to ~13 K, consistent with
recent results from the Herschel satellite. Further comparison of individual
regions show a strong correlation between the cold dust temperature and the Ks
band brightness, but not with the ionizing flux. The observed results imply
that the dominant heating source of cold dust at few hundred parsec scales are
due to the non-OB stars, even when associated with star forming regions.
