Dust and Gas in the Magellanic Clouds from the HERITAGE Herschel Key
  Project. I. Dust Properties and Insights into the Origin of the Submm Excess
  Emission
  The dust properties in the Large and Small Magellanic Clouds are studied
using the HERITAGE Herschel Key Project photometric data in five bands from 100
to 500 micron. Three simple models of dust emission were fit to the
observations: a single temperature blackbody modified by a power- law
emissivity (SMBB), a single temperature blackbody modified by a broken
power-law emissivity (BEMBB), and two blackbodies with different temperatures,
both modified by the same power-law emissivity (TTMBB). Using these models we
investigate the origin of the submm excess; defined as the submillimeter
(submm) emission above that expected from SMBB models fit to observations < 200
micron. We find that the BEMBB model produces the lowest fit residuals with
pixel-averaged 500 micron submm excesses of 27% and 43% for the LMC and SMC,
respectively. Adopting gas masses from previous works, the gas-to-dust ratios
calculated from our the fitting results shows that the TTMBB fits require
significantly more dust than are available even if all the metals present in
the interstellar medium (ISM) were condensed into dust. This indicates that the
submm excess is more likely to be due to emissivity variations than a second
population of colder dust. We derive integrated dust masses of (7.3 +/- 1.7) x
10^5 and (8.3 +/- 2.1) times 10^4 M(sun) for the LMC and SMC, respectively. We
find significant correlations between the submm excess and other dust
properties; further work is needed to determine the relative contributions of
fitting noise and ISM physics to the correlations.
