Millimeter Observations of Obscured Spitzer 24 μm Sources

October 2005 • 2005ApJ...632L..13L

Authors • Lutz, D. • Yan, L. • Armus, L. • Helou, G. • Tacconi, L. J. • Genzel, R. • Baker, A. J.

Abstract • We present MAMBO 1.2 mm observations of 40 extragalactic sources from the Spitzer First Look Survey that are bright in the mid-IR (S_24μm>1 mJy) but optically obscured (log[νF_ν(24 μm)/νF_ν(0.7 μm)]>1). We use these observations to search for cold dust emission, probing the similarity of their spectral energy distributions to star-forming IR galaxies or obscured AGNs. The sample as a whole is well detected at mean S_1.2mm=0.74+/-0.09 mJy and S_1.2mm/S_24μm=0.15+/-0.03. Seven (three) of the sources are individually detected at >3 σ (>5 σ) levels. Mean millimeter fluxes are higher for sources with the reddest mid-IR/optical colors. Optically faint but with relatively low millimeter-to-mid-IR ratios, the typical SEDs are inconsistent with redshifted SED shapes of local star-forming IR galaxies. They also differ from SEDs of typical submillimeter-selected galaxies, with the 24 μm sources that are individually detected by MAMBO possibly representing intermediate objects. Compared to star-forming galaxies, a stronger but optically obscured mid-IR component without associated strong far-IR emission has to be included. This component may be due to luminous optically obscured AGN, which would represent a significant part of the high-redshift AGN population.

Links

• PREPRINT http://arxiv.org/abs/astro-ph/0509058
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2005ApJ...632L..13L
• ELECTR https://doi.org/10.1086%2F497639
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2005ApJ...632L..13L
• PDF https://iopscience.iop.org/article/10.1086/497639/pdf
• DATA https://irsa.ipac.caltech.edu/bibdata/2005/L/2005ApJ...632L..13L.html
• SPIRES http://inspirehep.net/search?p=find+eprint+astro-ph/0509058