1204.2020 (Nicholas A. Bond et al.)

The Infrared Properties of Sources Matched in the WISE all-sky and Herschel-ATLAS Surveys    [PDF]

Nicholas A. Bond, Dominic J. Benford, Jonathan P. Gardner, Alexandre Amblard, Simone Fleuren, Andrew W. Blain, Loretta Dunne, Daniel J. B. Smith, Steve J. Maddox, Carlos Hoyos, Maarten Baes, David Bonfield, Nathan Bourne, Carrie Bridge, Sara Buttiglione, Antonio Cava, David Clements, Asantha Cooray, Ali Dariush, Gianfranco de Zotti, Simon Driver, Simon Dye, Steve Eales, Peter Eisenhardt, Rosalind Hopwood, Edo Ibar, Rob J. Ivison, Matt J. Jarvis, Lee Kelvin, Aaron S. G. Robotham, Pasquale Temi, Mark Thompson, Chao-Wei Tsai, Paul van der Werf, Edward L. Wright, Jingwen Wu, Lin Yan

We describe the infrared properties of sources detected over ~36 deg^2 of sky in the GAMA 15-hr equatorial field, using data from both the Herschel Astrophysical Terahertz Large-Area Survey (H-ATLAS) and Wide-field Infrared Survey (WISE). With 5-sigma point-source depths of 34 and 0.048 mJy at 250 micron and 3.4 micron, respectively, we are able to identify 50.6% of the H-ATLAS sources in the WISE survey, corresponding to a surface density of ~630 deg^{-2}. Approximately two-thirds of these sources have measured spectroscopic or optical/near-IR photometric redshifts of z<1. For sources with spectroscopic redshifts at z<0.3, we find a linear correlation between the infrared luminosity at 3.4 micron and that at 250 micron, with +-50% scatter over ~1.5 orders of magnitude in luminosity, ~10^9 - 10^{10.5} L_sun. By contrast, the matched sources without previously measured redshifts (r>~20.5) have 250-350 micron flux density ratios that suggest either high-redshift galaxies (z>~1.5) or optically faint low-redshift galaxies with unusually low temperatures (T<~20). Their small 3.4-250 micron flux ratios favor a high-redshift galaxy population, as only the most actively star-forming galaxies at low redshift (e.g., Arp 220) exhibit comparable flux density ratios. Furthermore, we find a relatively large AGN fraction (~30%) in a 12 micron flux-limited subsample of H-ATLAS sources, also consistent with there being a significant population of high-redshift sources in the no-redshift sample.

View original: http://arxiv.org/abs/1204.2020