Dust Reddened Quasars in First and Ukidss: Beyond the Tip of the Iceberg

Glikman, Eilat; Urrutia, T.; Lacy, Mark; Djorgovski, S. G.; Urry, C. Megan; Croom, S. M.; Schneider, Donald P.; Mahabal, A.; Graham, M. J.; Ge, Jian

doi:10.1088/0004-637x/778/2/127

Cited by 51 publications

(88 citation statements)

References 91 publications

(156 reference statements)

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“…Although the presence of broad emission lines is a characteristic of optical type 1 AGNs, in some cases it is difficult to detect broad lines due to obscuration in the optical spectral range (e.g., red AGNs) or intrinsically low luminosity diluted by host galaxy emission (e.g., Simpson 2005;Gilkman et al 2007Gilkman et al , 2013Woo et al 2014;Oh et al 2015;Kim et al 2015). Several studies tried to find hidden type 1 AGNs using different methods.…”

Section: Discussion : Comparison With Previous Workmentioning

confidence: 99%

A Systematic Search for Hidden Type 1 AGNs: Gas Kinematics and Scaling Relations

Eun

Woo

Bae

2017

ApJ

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We search type 1 AGNs among emission-line galaxies, that are typically classified as type 2 AGNs based on emission line flux ratios if a broad component in the Hα line profile is not properly investigated. Using ∼24,000 type 2 AGNs at z <0.1 initially selected from Sloan Digital Sky Survey Data Release 7 by Bae & Woo (2014), we identify a sample of 611 type 1 AGNs based on the spectral fitting results and visual inspection. These hidden type 1 AGNs have relatively low luminosity with a mean broad Hα luminosity, log L Hα = 40.73±0.32 erg s −1 and low Eddington ratio with a mean log L bol /L Edd = -2.04±0.34, while they do follow the black hole mass -stellar velocity dispersion relation defined by the inactive galaxies and the reverberation-mapped type 1 AGNs. We investigate ionized gas outflows based on the [O iii] λ5007 kinematics, which show relatively high velocity dispersion and velocity shift, indicating that the line-of-sight velocity and velocity dispersion of the ionized gas in type 1 AGNs is on average larger than that of type 2 AGNs.

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Section: Discussion : Comparison With Previous Workmentioning

confidence: 99%

A Systematic Search for Hidden Type 1 AGNs: Gas Kinematics and Scaling Relations

Eun

Woo

Bae

2017

ApJ

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“…We focused on observed quantities to explore the parameter space in which different classes of objects live. R W1 -is well correlated with R−K, an oft-used reddened AGN selection criterion (e.g., Brusa et al 2005;Glikman et al 2007Glikman et al , 2012Glikman et al , 2013Georgakakis et al 2009;Banerji et al 2012Banerji et al , 2015, and is thus helpful in such searches where K-band coverage deeper than 2MASS is lacking. Though R W1 -identifies AGNs similar to those selected based on R−K and R 3.6 m [ ] m -colors, the full-sky coverage of WISE, 35% sky coverage of SDSS, and 50% sky coverage of Pan-STARRsmake R W1 -a particularly suitable diagnostic to identify interesting AGN candidates for spectroscopic follow-up over a much larger area of the sky.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, an object that is optically faint while being infrared bright is a candidate hidden black hole. For instance, an oft-used diagnostic to identify red quasars is a color of R K -> 4-5 (Glikman et al 2004); this has been quite successful in identifying samples of reddened AGNs that are missed by optical-only surveys (e.g., Brusa et al 2005Brusa et al , 2015Glikman et al 2007Glikman et al , 2012Glikman et al , 2013Georgakakis et al 2009;Banerji et al 2012Banerji et al , 2015.…”

Section: Selecting Reddened Broad-lined Agnsmentioning

confidence: 99%

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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“…However, they have been found to be systematically biased against It it therefore important to understand to what extent various quasar samples suffer from biases against dust-reddened systems and quasars at high redshifts so that we can build more complete and representative samples. A large number of studies targeting reddened quasars have been executed in the past two decades (see, e.g., Webster et al 1995;Warren et al 2000;Gregg et al 2002;Richards et al 2003;Hopkins et al 2004;Glikman et al 2007Glikman et al , 2012Glikman et al , 2013Maddox et al 2008Maddox et al , 2012Urrutia et al 2009;Banerji et al 2012;Fynbo et al 2013;Krogager et al 2015), all trying to probe this underrepresented subset of quasars using a range of selection techniques that are less sensitive to dust obscuration. With the advent of large-area near-and mid-infrared surveys such as UKIDSS, WISE, and Spitzer (Wright et al 2010;Cutri & et al 2013;Lawrence et al 2007;Warren et al 2007;Werner et al 2004;Fazio et al 2004), the selection of quasars based on infrared (IR) photometry alone has been made possible as well (Donley et al 2008(Donley et al , 2012Peth et al 2011;Stern et al 2012;Mateos et al 2012;Secrest et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths

Heintz

Fynbo

Møller

et al. 2016

A&A

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The sub-population of quasars reddened by intrinsic or intervening clouds of dust are known to be underrepresented in optical quasar surveys. By defining a complete parent sample of the brightest and spatially unresolved quasars in the COSMOS field, we quantify to which extent this sub-population is fundamental to our understanding of the true population of quasars. By using the available multiwavelength data of various surveys in the COSMOS field, we built a parent sample of 33 quasars brighter than J = 20 mag, identified by reliable X-ray to radio wavelength selection techniques. Spectroscopic follow-up with the NOT/ALFOSC was carried out for four candidate quasars that had not been targeted previously to obtain a 100% redshift completeness of the sample. The population of high A V quasars (HAQs), a specific sub-population of quasars selected from optical/near-infrared photometry, some of which were shown to be missed in large optical surveys such as SDSS, is found to contribute 21% +9 −5 of the parent sample. The full population of bright spatially unresolved quasars represented by our parent sample consists of 39% +9 −8 reddened quasars defined by having A V > 0.1, and 21% +9 −5 of the sample having E(B − V) > 0.1 assuming the extinction curve of the Small Magellanic Cloud. We show that the HAQ selection works well for selecting reddened quasars, but some are missed because their optical spectra are too blue to pass the g − r color cut in the HAQ selection. This is either due to a low degree of dust reddening or anomalous spectra. We find that the fraction of quasars with contributing light from the host galaxy, causing observed extended spatial morphology, is most dominant at z 1. At higher redshifts the population of spatially unresolved quasars selected by our parent sample is found to be representative of the full population of bright active galactic nuclei at J < 20 mag. This work quantifies the bias against reddened quasars in studies that are based solely on optical surveys.

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Dust Reddened Quasars in First and Ukidss: Beyond the Tip of the Iceberg

Cited by 51 publications

References 91 publications

A Systematic Search for Hidden Type 1 AGNs: Gas Kinematics and Scaling Relations

A Systematic Search for Hidden Type 1 AGNs: Gas Kinematics and Scaling Relations

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

Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths

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