MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE<i>WIDE-FIELD INFRARED SURVEY EXPLORER</i>. I. CHARACTERIZING<i>WISE</i>-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS

Stern, Daniel; Assef, Roberto J.; Benford, Dominic J.; Blain, A. W.; Cutri, R. M.; Dey, Arjun; Eisenhardt, Peter; Griffith, R. L.; Jarrett, T. H.; Lake, Sean E.; Masci, Frank J.; Petty, Sara; Stanford, S. A.; Tsai, Chao-Wei; Wright, E. L.; Yan, Lin; Harrison, Fiona A.; Madsen, Kristin K.

doi:10.1088/0004-637x/753/1/30

Cited by 799 publications

(1,093 citation statements)

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“…3. We find that the W W 1 2 -color cut to select AGNs from Stern et al (2012) and Assef et al (2013) (parameterized by the X-ray HR) and R W1 - (Figures 20-21). This lack of correlation likely results from the fact that many of the Stripe 82X AGNs are broadlined objects, where circumnuclear obscuration affecting X-ray emission is presumably occurring out of the line of sight and HRs as a proxy for N H areof limited utility when the X-ray spectra are complex.…”

Section: Resultsmentioning

confidence: 88%

“…How does this compare with AGNs selected on the basis of their mid-infrared colors only? Stern et al (2012) …”

Section: Discussionmentioning

confidence: 99%

“…Obscured AGNs, both narrow-lined and reddened broadlined objects, have also been identified using: n n ), where [3.6] is the Spitzer magnitude at 3.6 μm (Fiore et al 2008(Fiore et al , 2009Yan et al 2010;Melbourne et al 2011 Wright et al 2010) flux at 4.6 μm (Stern et al 2012;Yan et al 2013;Donoso et al 2014). …”

Section: Selecting Reddened Broad-lined Agnsmentioning

confidence: 99%

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On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

LaMassa

Civano

Brusa

et al. 2016

ApJ

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Capitalizing on the all-sky coverage of WISEand the 35% and 50% sky coverage from Sloan Digital Sky Survey and Pan-STARRS, respectively, we explore the efficacy of-, as a color diagnostic to identify obscured supermassive black hole accretion in wide-area X-ray surveys. We use the ∼16.5 deg 2 Stripe 82 X-ray survey data as a testbed to compare R W1 -with R−K, an oft-used obscured active galactic nucleus (AGN) selection criterion, and examine where different classes of objects lie in this parameter space. Most stars follow a well-defined path in R−K versus R W1space. We demonstrate that optically normal galaxies hosting X-ray AGNs at redshifts z 0.5 1 < < can be recovered with an R W1 4 -> colorcut, while they typically are not selected as AGNs based on their W W 1 2 -colors. Additionally, different observed X-ray luminosity bins favor different regions in R W1 -parameter space: moderate-luminosity AGNs > -erg s −1 ) have bluer colors; higher spectroscopic completeness of the Stripe 82X sample is needed to determine whether this is a selection effect or an intrinsic property. Finally, we parameterize X-ray obscuration of Stripe 82X AGNs by calculating their hardness ratios (HRs) and find no clear trends between HR and optical reddening. Our results will help inform best-effort practices in followingup obscured AGN candidates in current and future wide-area, shallow X-ray surveys, including the all-sky eROSITA mission.

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Section: Resultsmentioning

confidence: 88%

“…How does this compare with AGNs selected on the basis of their mid-infrared colors only? Stern et al (2012) …”

Section: Discussionmentioning

confidence: 99%

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On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

LaMassa

Civano

Brusa

et al. 2016

ApJ

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“…A further check on any contamination by non-AGN components may be obtained from the mid-infrared colour of NGC 7674 as tabulated in the WISE/AllWISE catalogue (Wright et al 2010;Cutri et al 2013). The W1 − W2 colour is 1.16 ±0.03 mag, which places the source above the colour threshold of W1 -W2 > 0.8 identified by Stern et al (2012), where the mid-infrared emission is likely to be AGN-dominated.…”

Section: Multiwavelength Comparisonsmentioning

confidence: 76%

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

Gandhi

Annuar

Lansbury

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe XXVI ionised line (EW ≈ 0.2 keV). We construct an updated longterm X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 years, following a high flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ∼ 3.2 pc under the switchedoff AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (N H ) of 3 × 10 24 cm −2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 10 43 erg s −1 . Realistic uncertainties span the range of ≈ (1-13) × 10 43 erg s −1 . The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionised Fe emission. It exemplifies the difficulty of identification and proper characterisation of distant CTAGN based on the strength of the neutral Fe Kα line.

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“…Studying AGNs over a range of redshift allows us to discover how supermassive black holes evolve over cosmic time to the present day. As AGNs emit energy over a range of wavelengths, they can be identified by various signatures, including optical and ultraviolet light from the accretion disk feeding the black hole (Koratkar & Blaes 1999), optical emission from gas ionized by accretion disk photons (Baldwin et al 1981;Veilleux & Osterbrock 1987;Vanden Berk et al 2001), X-ray emission from the AGN corona (Haardt & Maraschi 1991;Brandt & Alexander 2015), mid-infrared emission from AGN heated circumnuclear dust (Spinoglio & Malkan 1989;Lacy et al 2004;Stern et al 2005;Donley et al 2012;Stern et al 2012;Assef et al 2013), and fine-structure emission lines (Farrah et al 2007;Weaver et al 2010;Meléndez et al 2014), and radio emission from jets launched by the accretion disk (Kellermann et al 1989;Hooper et al 1995). These different selection criteria favor different parts of the AGN population, and by combining these methods, a comprehensive view of black hole growth is revealed.…”

Section: Introductionmentioning

confidence: 99%

THE 31 DEG² RELEASE OF THE STRIPE 82 X-RAY SURVEY: THE POINT SOURCE CATALOG

LaMassa

Urry²,

Cappelluti

et al. 2016

ApJ

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We release the next installment of the Stripe 82 X-ray survey point-source catalog, which currently covers 31.3 deg 2 of the Sloan Digital Sky Survey (SDSS) Stripe 82 Legacy field. In total, 6181 unique X-ray sources are significantly detected with XMM-Newton (>5σ) and Chandra (>4.5σ). This catalog release includes data from XMM-Newton cycle AO 13, which approximately doubled the Stripe 82X survey area. The flux limits of the Stripe 82X survey are 8.7×10 −16 erg s −1 cm −2 , 4.7×10 −15 erg s −1 cm −2 , and 2.1×10 −15 erg s −1 cm −2 in the soft (0.5-2 keV), hard (2-10 keV), and full bands (0.5-10 keV), respectively, with approximate half-area survey flux limits of 5.4×10 −15 erg s −1 cm −2 , 2.9×10 −14 erg s −1 cm −2 , and 1.7×10 −14 erg s −1 cm −2 . We matched the X-ray source lists to available multi-wavelength catalogs, including updated matches to the previous release of the Stripe 82X survey; 88% of the sample is matched to a multi-wavelength counterpart. Due to the wide area of Stripe 82X and rich ancillary multi-wavelength data, including coadded SDSS photometry, mid-infrared WISE coverage, near-infrared coverage from UKIDSS and VISTA Hemisphere Survey, ultraviolet coverage from GALEX, radio coverage from FIRST, and far-infrared coverage from Herschel, as well as existing ∼30% optical spectroscopic completeness, we are beginning to uncover rare objects, such as obscured high-luminosity active galactic nuclei at high-redshift. The Stripe 82X point source catalog is a valuable data set for constraining how this population grows and evolves, as well as for studying how they interact with the galaxies in which they live.

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MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THEWIDE-FIELD INFRARED SURVEY EXPLORER. I. CHARACTERIZINGWISE-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS

Cited by 799 publications

References 105 publications

On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

THE 31 DEG² RELEASE OF THE STRIPE 82 X-RAY SURVEY: THE POINT SOURCE CATALOG

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MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THEWIDE-FIELD INFRARED SURVEY EXPLORER. I. CHARACTERIZINGWISE-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS

Cited by 799 publications

References 105 publications

On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

On R − W1 as a Diagnostic to Discover Obscured Active Galactic Nuclei in Wide-Area X-Ray Surveys

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

THE 31 DEG2 RELEASE OF THE STRIPE 82 X-RAY SURVEY: THE POINT SOURCE CATALOG

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THE 31 DEG² RELEASE OF THE STRIPE 82 X-RAY SURVEY: THE POINT SOURCE CATALOG