2005/02/10 by J. R. Houck, B. T. Soifer, D. Weedman +19 · 15 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/429405
published as Astrophys.J.622:L105-L108,2005 · Accepted for publication on 7 Feb 2005 in ApJL. 7 pages 2 figures
arxiv created 2005/02/10 · openalex publication_date 2005/03/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We have surveyed a field covering 9.0 deg 2 within the NOAO Deep Wide-Field Survey region in Bootes with the Multiband Imaging Photometer on the Spitzer Space Telescope ( SST ) to a limiting 24 μm flux density of 0.3 mJy. Thirty-one sources from this survey with F 24 μm > 0.75 mJy that are optically very faint ( R ≳ 24.5 mag) have been observed with the low-resolution modules of the Infrared Spectrograph on SST (IRS). Redshifts derived primarily from strong silicate absorption features are reported here for 17 of these sources; 10 of these are optically invisible ( R ≳ 26 mag), with no counterpart in B W , R , or I . The observed redshifts for 16 sources are 1.7 < z < 2.8. These represent a newly discovered population of highly obscured sources at high redshift with extreme infrared-to-optical ratios. Using IRS spectra of local galaxies as templates, we find that a majority of the sources have mid-infrared spectral shapes most similar to ultraluminous infrared galaxies powered primarily by active galactic nuclei. Assuming that the same templates also apply at longer wavelengths, bolometric luminosities exceed 10 13 L ☉ .