A search for debris disks in the Herschel ATLAS
  Aims: We aim to demonstrate that the Herschel ATLAS (H-ATLAS) is suitable for
a blind and unbiased survey for debris disks by identifying candidate debris
disks associated with main sequence stars in the initial science demonstration
field of the survey. We show that H-ATLAS reveals a population of
far-infrared/sub-mm sources that are associated with stars or star-like objects
on the SDSS main-sequence locus. We validate our approach by comparing the
properties of the most likely candidate disks to those of the known population.
Methods: We use a photometric selection technique to identify main sequence
stars in the SDSS DR7 catalogue and a Bayesian Likelihood Ratio method to
identify H-ATLAS catalogue sources associated with these main sequence stars.
Following this photometric selection we apply distance cuts to identify the
most likely candidate debris disks and rule out the presence of contaminating
galaxies using UKIDSS LAS K-band images. Results: We identify 78 H-ATLAS
sources associated with SDSS point sources on the main-sequence locus, of which
two are the most likely debris disk candidates: H-ATLAS J090315.8 and H-ATLAS
J090240.2. We show that they are plausible candidates by comparing their
properties to the known population of debris disks. Our initial results
indicate that bright debris disks are rare, with only 2 candidates identified
in a search sample of 851 stars. We also show that H-ATLAS can derive useful
upper limits for debris disks associated with Hipparcos stars in the field and
outline the future prospects for our debris disk search programme.
