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 boötes field

R. J. Assef, D. Stern, C. S. Kochanek, A. W. Blain, M. Brodwin, M. J I Brown, E. Donoso, P. R M Eisenhardt, Buell Tomasson Jannuzi, T. H. Jarrett, S. A. Stanford, C. W. Tsai, J. Wu, L. Yan

Research output: Contribution to journalArticle

184 Citations (Scopus)

Abstract

Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg2 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 μm and 4.6 μm, respectively. Here we extend this study using the larger 9 deg2 NOAO Deep Wide-Field Survey Boötes 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-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 bolometric 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 AGN ∼ 3 × 1044 erg s-1, 29% ± 7% of AGNs are observed as Type 1, while at ∼4 × 1045 erg s-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.

Original languageEnglish (US)
Article number26
JournalAstrophysical Journal
Volume772
Issue number1
DOIs
StatePublished - Jul 20 2013

Fingerprint

Wide-field Infrared Survey Explorer
active galactic nuclei
erg
dust
field survey
occultation
color
luminosity
distribution
energy
spectral energy distribution
photometry

Keywords

  • galaxies: active
  • methods: statistical
  • quasars: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

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 boötes field. / Assef, R. J.; Stern, D.; Kochanek, C. S.; Blain, A. W.; Brodwin, M.; Brown, M. J I; Donoso, E.; Eisenhardt, P. R M; Jannuzi, Buell Tomasson; Jarrett, T. H.; Stanford, S. A.; Tsai, C. W.; Wu, J.; Yan, L.

In: Astrophysical Journal, Vol. 772, No. 1, 26, 20.07.2013.

Research output: Contribution to journalArticle

Assef, RJ, Stern, D, Kochanek, CS, Blain, AW, Brodwin, M, Brown, MJI, Donoso, E, Eisenhardt, PRM, Jannuzi, BT, Jarrett, TH, Stanford, SA, Tsai, CW, Wu, J & Yan, L 2013, '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 boötes field', Astrophysical Journal, vol. 772, no. 1, 26. https://doi.org/10.1088/0004-637X/772/1/26
Assef, R. J. ; Stern, D. ; Kochanek, C. S. ; Blain, A. W. ; Brodwin, M. ; Brown, M. J I ; Donoso, E. ; Eisenhardt, P. R M ; Jannuzi, Buell Tomasson ; Jarrett, T. H. ; Stanford, S. A. ; Tsai, C. W. ; Wu, J. ; Yan, L. / 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 boötes field. In: Astrophysical Journal. 2013 ; Vol. 772, No. 1.
@article{8ebcd1382c6d43bc820d9ea9395b2ffe,
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 bo{\"o}tes field",
abstract = "Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg2 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 μm and 4.6 μm, respectively. Here we extend this study using the larger 9 deg2 NOAO Deep Wide-Field Survey Bo{\"o}tes 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-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 bolometric 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 AGN ∼ 3 × 1044 erg s-1, 29{\%} ± 7{\%} of AGNs are observed as Type 1, while at ∼4 × 1045 erg s-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.",
keywords = "galaxies: active, methods: statistical, quasars: general",
author = "Assef, {R. J.} and D. Stern and Kochanek, {C. S.} and Blain, {A. W.} and M. Brodwin and Brown, {M. J I} and E. Donoso and Eisenhardt, {P. R M} and Jannuzi, {Buell Tomasson} and Jarrett, {T. H.} and Stanford, {S. A.} and Tsai, {C. W.} and J. Wu and L. Yan",
year = "2013",
month = "7",
day = "20",
doi = "10.1088/0004-637X/772/1/26",
language = "English (US)",
volume = "772",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - 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 boötes field

AU - Assef, R. J.

AU - Stern, D.

AU - Kochanek, C. S.

AU - Blain, A. W.

AU - Brodwin, M.

AU - Brown, M. J I

AU - Donoso, E.

AU - Eisenhardt, P. R M

AU - Jannuzi, Buell Tomasson

AU - Jarrett, T. H.

AU - Stanford, S. A.

AU - Tsai, C. W.

AU - Wu, J.

AU - Yan, L.

PY - 2013/7/20

Y1 - 2013/7/20

N2 - Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg2 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 μm and 4.6 μm, respectively. Here we extend this study using the larger 9 deg2 NOAO Deep Wide-Field Survey Boötes 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-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 bolometric 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 AGN ∼ 3 × 1044 erg s-1, 29% ± 7% of AGNs are observed as Type 1, while at ∼4 × 1045 erg s-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.

AB - Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg2 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 μm and 4.6 μm, respectively. Here we extend this study using the larger 9 deg2 NOAO Deep Wide-Field Survey Boötes 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-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 bolometric 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 AGN ∼ 3 × 1044 erg s-1, 29% ± 7% of AGNs are observed as Type 1, while at ∼4 × 1045 erg s-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.

KW - galaxies: active

KW - methods: statistical

KW - quasars: general

UR - http://www.scopus.com/inward/record.url?scp=84879958562&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84879958562&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/772/1/26

DO - 10.1088/0004-637X/772/1/26

M3 - Article

AN - SCOPUS:84879958562

VL - 772

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 26

ER -