Unveiling Far-Infrared Counterparts of Bright Submillimeter Galaxies
  Using PACS Imaging
  We present a search for Herschel-PACS counterparts of dust-obscured,
high-redshift objects previously selected at submillimeter and millimeter
wavelengths in the Great Observatories Origins Deep Survey North field. We
detect 22 of 56 submillimeter galaxies (39%) with a SNR of >=3 at 100 micron
down to 3.0 mJy, and/or at 160 micron down to 5.7 mJy. The fraction of SMGs
seen at 160 micron is higher than that at 100 micron. About 50% of
radio-identified SMGs are associated with PACS sources. We find a trend between
the SCUBA/PACS flux ratio and redshift, suggesting that these flux ratios could
be used as a coarse redshift indicator. PACS undetected submm/mm selected
sources tend to lie at higher redshifts than the PACS detected ones. A total of
12 sources (21% of our SMG sample) remain unidentified and the fact that they
are blank fields at Herschel-PACS and VLA 20 cm wavelength may imply higher
redshifts for them than for the average SMG population (e.g., z>3-4). The
Herschel-PACS imaging of these dust-obscured starbursts at high-redshifts
suggests that their far-infrared spectral energy distributions have
significantly different shapes than template libraries of local infrared
galaxies.
