Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published December 10, 2008 | Published
Journal Article Open

The nature of faint SPITZER-selected dust-obscured galaxies

Abstract

We use deep far-IR, submillimeter, radio, and X-ray imaging and mid-IR spectroscopy to explore the nature of a sample of Spitzer-selected dust-obscured galaxies (DOGs) in GOODS-N. A sample of 79 galaxies satisfy the criteria R − [ 24] > 14 (Vega) down to S_(24) > 100 μJy (median flux density S_(24) = 180 μJy). Twelve of these galaxies have IRS spectra available, which we use to measure redshifts and classify these objects as being dominated by star formation or active galactic nucleus (AGN) activity in the mid-IR. The IRS spectra and Spitzer photometric redshifts confirm that the DOGs lie in a tight redshift distribution around z ~ 2. Based on mid-IR colors, 80% of DOGs are likely dominated by star formation; the stacked X-ray emission from this subsample of DOGs is also consistent with star formation. Since only a small number of DOGs are individually detected at far-IR and submillimeter wavelengths, we use a stacking analysis to determine the average flux from these objects and plot a composite IR (8-1000 μm) spectral energy distribution (SED). The average luminosity of these star-forming DOGs is L_(IR) ~ 1 × 10^(12)L☉. We compare the average star-forming DOG to the average bright (S_(850) > 5 mJy) submillimeter galaxy (SMG); the S_(24) > 100 μJy DOGs are 3 times more numerous but 8 times less luminous in the IR. The far-IR SED shape of DOGs is similar to that of SMGs (average dust temperature of around 30 K), but DOGs have a higher mid-IR-to-far-IR flux ratio. The average star formation-dominated DOG has a star formation rate of 200 M☉ yr^(−1), which, given their space density, amounts to a contribution of 0.01 M☉yr^(−1) Mpc^(−3) (or 5%-10%) to the star formation rate density at z ~ 2.

Additional Information

© 2008 The American Astronomical Society. Received 2008 June 24, accepted for publication 2008 August 20. We thank the referee for constructive comments on this paper. We are grateful to Emanuele Daddi and Anna Sajina for insightful discussions. A. P. acknowledges support provided by NASA through the Spitzer Space Telescope Fellowship Program, through a contract issued by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The research of A. P., A. D., M. B., and M. E. D. is supported in part by NOAO, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. D. M. A. thanks the Royal Society for support. This work is based on observations made with the Spitzer Space Telescope,which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. We acknowledge L. Simard for leading the GOODS-N WIRCAM K-band proposal and L. Albert and the Terapix team for help on the WIRCAM data processing.

Attached Files

Published - Pope2008p313Astrophys_J.pdf

Files

Pope2008p313Astrophys_J.pdf
Files (273.4 kB)
Name Size Download all
md5:4fb5b07c14c22c4e63525592c7e46bf3
273.4 kB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023