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.Comment: 6 pages, 4 figures. ApJ Letters in pres

FIR Measurements of Lyα Emitters at z

One remaining open question regarding the physical properties of Ly alpha emitters (LAEs) is their dust content and evolution with redshift. The variety of results is large and with those reported by now it is difficult to establish clear relations between dust, other fundamental parameters of galaxies (star formation rate, metallicity, or age), and redshift. In this Letter, we report Herschel PACS-100 mu m, PACS-160 mu m, and Spitzer MIPS-24 mu m detections of a sample of spectroscopically GALEX selected LAEs at z similar to 0.3 and similar to 1.0. Five out of ten and one out of two LAEs are detected in, at least, one PACS band at z similar to 0.3 and similar to 1.0, respectively. These measurements have a great importance given that they allow us to quantify, for the first time, the dust content in LAEs from direct FIR observations. MIPS-24 mu m detections allow us to determine the IR properties of the PACS-undetected LAEs. We obtain that mid-IR/FIR-detected star-forming (SF) LAEs at z similar to 0.3 have dust content within 0.75 less than or similar to A(1200 angstrom) less than or similar to 2.0, with a median value of A(1200 angstrom) similar to 1.1. This range broadens up to 0.75 less than or similar to A(1200 angstrom) less than or similar to 2.5 when considering the LAEs at z similar to 1.0. Only one SF LAE is undetected both in MIPS-24 mu m and PACS, with A(1200 angstrom) less than or similar to 0.75. These results seem to be larger than those reported for high-redshift LAEs and, therefore, although an evolutionary trend is not clearly seen, it could point out that low-redshift LAEs are dustier than high-redshift ones. However, the diverse methods used could introduce a systematic offset in the results