Bertincourt, B. and Helou, G. and Appleton, P. and Ogle, P. and Lagache, G. and Brooke, T. and Smith, J-D. and Sheth, K. and Dale, D. and Harwit, M. and Puget, J-L. and Roussel, H. (2009) A Spitzer Unbiased Ultradeep Spectroscopic Survey. Astrophysical Journal, 705 (1). pp. 68-88. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20091109-092443054
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We carried out an unbiased, spectroscopic survey using the low-resolution module of the infrared spectrograph (IRS) onboard Spitzer targeting two 2.6 square arcminute regions in the GOODS-North field. The IRS was used in a spectral mapping mode with 5 hr of effective integration time per pixel. One region was covered between 14 and 21 μm and the other between 20 and 35 μm. We extracted spectra for 45 sources. About 84% of the sources have reported detections by GOODS at 24 μm, with a median f_ν(24 μm) ~ 100 μJy. All but one source are detected in all four IRAC bands, 3.6 to 8 μm. We use a new cross-correlation technique to measure redshifts and estimate IRS spectral types; this was successful for ~60% of the spectra. Fourteen sources show significant polycyclic aromatic hydrocarbon emission, four mostly SiO absorption, eight present mixed spectral signatures (low PAH and/or SiO) and two show a single line in emission. For the remaining 17, no spectral features were detected. Redshifts range from z ~ 0.2 to z ~ 2.2, with a median of 1. IR luminosities are roughly estimated from 24 μm flux densities, and have median values of 2.2 × 10^(11) L_⊙ and 7.5 × 10^(11) L_⊙ at z ~ 1 and z ~ 2, respectively. This sample has fewer active galactic nuclei than previous faint samples observed with the IRS, which we attribute to the fainter luminosities reached here.
|Additional Information:||© 2009 The American Astronomical Society. Received 2009 January 6; accepted 2009 September 10; published 2009 October 7. We thank Aaron Stephen for help with the X-ray data. This work is based on observation obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Support for this work was provided by NASA through an award issued by JPL/Caltech, as well as the French National Agency for Research under programs ANR-06-BLAN-0170 and ANR- 05-BLAN-0289-02. This research has made use of the NASA/ IPAC Extragalactic Database which is operated by JPL/Caltech, under contract with NASA. Facilities: Spitzer (IRS).|
|Subject Keywords:||galaxies: starburst; infrared: galaxies|
|Official Citation:||A Spitzer Unbiased Ultradeep Spectroscopic Survey B. Bertincourt, G. Helou, P. Appleton, P. Ogle, G. Lagache, T. Brooke, J-D. Smith, K. Sheth, D. Dale, M. Harwit, J-L. Puget, and H. Roussel 2009 ApJ 705 68-88 doi: 10.1088/0004-637X/705/1/68|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||16 Nov 2009 17:09|
|Last Modified:||26 Dec 2012 11:32|
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