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Title: MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. II. PROPERTIES OF WISE-SELECTED ACTIVE GALACTIC NUCLEI IN THE NDWFS BOOeTES FIELD

Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg{sup 2} COSMOS field, finding that a simple criterion W1-W2 {>=} 0.8 provides a highly reliable and complete AGN sample for W2 < 15.05, where the W1 and W2 passbands are centered at 3.4 {mu}m and 4.6 {mu}m, respectively. Here we extend this study using the larger 9 deg{sup 2} NOAO Deep Wide-Field Survey Booetes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1-W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130 {+-} 4 deg{sup -2} AGN candidates for W2 < 17.11 with 90% reliability. Using the extensive UV through mid-IR broadband photometry available in this field, we study the spectral energy distributions of WISE AGN candidates. We find that, as expected, the WISE AGN selection can identify highly obscured AGNs, but that it is biased toward objects where the AGN dominates the bolometricmore » luminosity output. We study the distribution of reddening in the AGN sample and discuss a formalism to account for sample incompleteness based on the step-wise maximum-likelihood method of Efstathiou et al. The resulting dust obscuration distributions depend strongly on AGN luminosity, consistent with the trend expected for a receding torus. At L{sub AGN} {approx} 3 Multiplication-Sign 10{sup 44} erg s{sup -1}, 29% {+-} 7% of AGNs are observed as Type 1, while at {approx}4 Multiplication-Sign 10{sup 45} erg s{sup -1} the fraction is 64% {+-} 13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ; ;  [6] ;  [7] ;  [8] ;  [9]
  1. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-236, Pasadena, CA 91109 (United States)
  2. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  3. Physics and Astronomy, University of Leicester, 1 University Road, Leicester, LE1 7RH (United Kingdom)
  4. Department of Physics, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States)
  5. School of Physics, Monash University, Clayton 3800, Victoria (Australia)
  6. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  7. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
  8. Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States)
  9. UCLA Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States)
Publication Date:
OSTI Identifier:
22121883
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 772; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; COLOR; COSMIC DUST; ENERGY SPECTRA; GALAXIES; GALAXY NUCLEI; INFRARED SURVEYS; LUMINOSITY; MAXIMUM-LIKELIHOOD FIT; PHOTOMETRY