2006/06/29 by D. W. Weedman, B. T. Soifer, Lei Hao +25 · 2 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Galaxy #Infrared #Photometry (optics) #Physics #Redshift #Spectral energy distribution #Spectral line #Spectrograph #Spitzer Space Telescope #Stars #Stellar, planetary, and galactic studies #Telescope #astro-ph
paper · pdf · doi:10.1086/507322
published as Astrophys.J.651:101-112,2006 · Accepted by ApJ
arxiv created 2006/06/29 · openalex publication_date 2006/10/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope ( Spitzer ) for 58 sources having f ν (24 μm) > 0.75 mJy. Sources were chosen from a survey of 8.2 deg 2 within the NOAO Deep Wide-Field Survey region in Boötes (NDWFS) using the Multiband Imaging Photometer (MIPS) on Spitzer . Most sources are optically very faint ( I > 24 mag). Redshifts have previously been determined for 34 sources, based primarily on the presence of a deep 9.7 μm silicate absorption feature, with a median z of 2.2. Spectra are presented for the remaining 24 sources for which we were previously unable to determine a confident redshift because the IRS spectra show no strong features. Optical photometry from the NDWFS and infrared photometry with MIPS and the Infrared Array Camera on Spitzer (IRAC) are given, with K photometry from the Keck I telescope for some objects. The sources without strong spectral features have overall spectral energy distributions (SEDs) and distributions among optical and infrared fluxes that are similar to those for the sources with strong absorption features. Nine of the 24 sources are found to have feasible redshift determinations based on fits of a weak silicate absorption feature. Results confirm that the "1 mJy" population of 24 μm Spitzer sources that are optically faint is dominated by dusty sources with spectroscopic indicators of an obscured AGN rather than a starburst. There remain 14 of the 58 sources observed in Boötes for which no redshift could be estimated, and 5 of these sources are invisible at all optical wavelengths.