The Submillimetre Properties of Ultraluminous Infrared Galaxies
  We present the results of SCUBA observations of a complete sample of local
ULIRGs. Twenty of the initial sample of 23 sources are detected at 850 um and
nearly half of the objects are also detected at 450 um. This data is combined
with existing observations of a further seven ULIRGs to produce the largest
sample of submm observations of ULIRGs currently available. We use similar
techniques to the SLUGS survey to fit dust spectral energy distributions (SEDs)
to their far-IR emission. We find that ULIRGs have a higher dust temperature
than lower luminosity objects (42K compared to 35K) and a steeper emissivity
index. For those objects where 450 um fluxes are available we also attempt a
two component dust SED fit, with warm and cool dust and a dust emissivity index
of beta=2. Such a model has been found to be a good fit to lower luminosity
systems. We find that it also works well for ULIRGs, but that ULIRGs have a
smaller cold dust component. Comparison of the dust mass derived for ULIRGs and
more normal spiral galaxies suggests that the dust content of a ULIRG is simply
the combined dust content of the two galaxies whose merger has triggered the
ULIRG activity. We examine the high end of the 850 um luminosity function and
find results consistent with those of the earlier SLUGS survey. We also find
that ULIRGs make up only about 50% of the high end of the 850 um luminosity
function, with LIRGs containing a large mass of cool dust likely to be
responsible for the rest.
