Thursday April 19th, 2013

Far-IR Emission From Dust-Obscured Galaxies

J.A. Calanog, J. Wardlow, Hai Fu, A. Cooray, R.J. Assef, J. Bock, C.M. Casey, A. Conley, D. Farrah, E. Ibar, J. Kartaltepe, G. Magdis, L. Marchetti, S.J. Oliver, I. Perez-Fournon, D. Riechers, D. Rigopoulou, I.G. Roseboom, B. Schulz,Douglas Scott, M. Symeonidis, M. Vaccari, M. Viero, M. Zemcov
(Submitted on 16 Apr 2013)

Dust-obscured galaxies (DOGs) are a UV-faint, IR-bright galaxy population that reside at z~2 and are believed to be in a phase of dusty star-forming and AGN activity. We present far-IR observations of a complete sample of DOGs in the 2 deg^2 of COSMOS. The 3077 DOGs have <z>=1.9+/-0.3 and are selected from 24 um and r+ observations using a color cut of r+ – [24] >= 7.5 (AB mag) and S24 >= 100 uJy. Based on the mid-IR SEDs, 47% are star-formation dominated and 10% are AGN-dominated. We use SPIRE far-IR photometry from HerMES to calculate the IR luminosity and characteristic dust temperature for the 1572 (51%) DOGs that are detected at 250 um (>=3sigma). For the remaining 1505 (49%) that are undetected, we perform a median stacking analysis to probe fainter luminosities. Detected and undetected DOGs have average IR luminosities of (2.8+/-0.4) x 10^12 L_Sun and (0.77+/-0.08) x 10^12L_Sun, and dust temperatures of 34+/-7 K and 31+/-3 K, respectively. Using far-IR observations, DOGs contribute 30% to the 24 um-selected galaxies’ IR luminosity. If the IR luminosity is extrapolated using the 24 um flux density alone, it is overestimated by a factor of 2 on average. DOGs contribute 10-30% to the total star formation rate density of the Universe at z=1.5-2.5, dominated by 250{\mu}m detected and bump DOGs, compared to around 40% for all 24 um galaxies above our flux limit. DOGs have a large scatter about the star-formation main sequence and their specific star-formation rates show that the observed phase of star-formation could be responsible for their observed stellar mass at z~2.

Comments: 11 Pages, 9 figures, ApJ submitted
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)
Cite as: arXiv:1304.4593 [astro-ph.CO]
(or arXiv:1304.4593v1 [astro-ph.CO] for this version)
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