Obscured Active Galactic Nuclei and the X‐Ray, Optical, and Far‐Infrared Number Counts of Active Galactic Nuclei in the GOODS Fields

Treister, Ezequiel; Urry, C. Megan; Chatzichristou, E.; Bauer, F. E.; Alexander, D. M.; Koekemoer, Anton M.; Duyne, J. Van; Brandt, W. N.; Bergeron, J.; Stern, Daniel; Moustakas, Leonidas A.; Chary, R.-R.; Conselice, Christopher J.; Cristiani, S.; Grogin, Norman A.

doi:10.1086/424891

Cited by 151 publications

(180 citation statements)

References 66 publications

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“…At the same time, these faint red X-ray AGN were copious emitters of infrared radiation (Treister et al 2004, fully consistent with the unification paradigm. It also became apparent early on that, as for optically-selected quasars, the evolution of X-ray selected AGN is luminosity dependent, with high-luminosity AGN evolving earlier and more rapidly than low-luminosity AGN Cowie et al 2003); this luminosity-dependent density evolution had not been incorporated in earlier population synthesis models for the X-ray background.…”

Section: Finding Obscured Agnsupporting

confidence: 70%

“…A number of authors pointed out these problems (e.g., Mainieri et al 2005;Rosati et al 2002;, and Franceschini et al (2002a) suggested that "the unification scheme based on a simple orientation effect fails at high redshifts" and that the production of the X-ray background by a collection of obscured AGN "requires major revision. "At the same time, these faint red X-ray AGN were copious emitters of infrared radiation (Treister et al 2004, fully consistent with the unification paradigm. It also became apparent early on that, as for optically-selected quasars, the evolution of X-ray selected AGN is luminosity dependent, with high-luminosity AGN evolving earlier and more rapidly than low-luminosity AGN Cowie et al 2003); this luminosity-dependent density evolution had not been incorporated in earlier population synthesis models for the X-ray background.…”

supporting

confidence: 70%

“…Our approach was to connect surveys at different wavelengths by assuming something sensible about AGN spectral energy distributions (SEDs), then combining those with wellmeasured luminosity functions and evolution to understand the source counts and redshift distributions of AGN selected at a given flux limit at any wavelength (Treister et al 2004 ). An alternative approach is to model only the X-ray spectra of AGN and to fit the X-ray background alone with a mixture of obscured and unobscured AGN (Comastri et al 1995;Gilli et al 2001Gilli et al , 2007; this constrains the demographics but does not connect the X-ray sources to those detected at optical and infrared wavelengths -and thus does not use those additional constraints on the AGN demographics, nor does it allow a quantitative estimate of the important effect of optical or infrared flux limits on the survey content or spectroscopic identifications.…”

Section: Connecting X-ray Optical and Infrared Surveysmentioning

confidence: 99%

“…The resulting number counts and redshift distributions for GOODS do not change, since only a restricted luminosity range (primarily 10 43−44 ergs/s) is probed by that survey. In all work subsequent to Treister et al (2004) -on infrared counts, X-ray background, and evolution of obscuration (see below) -we incorporated this luminosity dependence.Our population synthesis model predicts, with very little freedom, the spectrum of the X-ray background. We simply sum the X-ray emission from all the AGN.…”

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confidence: 99%

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Supermassive black holes in deep multiwavelength surveys

Urry¹,

Treister²

2011

Black Holes

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In recent years deep X-ray and infrared surveys have provided an efficient way to find accreting supermassive black holes, otherwise known as active galactic nuclei (AGN), in the young universe. Such surveys can, unlike optical surveys, find AGN obscured by high column densities of gas and dust. In those cases, deep optical data show only the host galaxy, which can then be studied in greater detail than in unobscured AGN. Some years ago the hard spectrum of the Xray "background" suggested that most AGN were obscured. Now GOODS, MUSYC, COSMOS and other surveys have confirmed this picture and given important quantitative constraints on AGN demographics. Specifically, we show that most AGN are obscured at all redshifts and the amount of obscuration depends on both luminosity and redshift, at least out to redshift z ∼ 2, the epoch of substantial black holes and galaxy growth. Larger-area deep infrared and hard X-ray surveys will be needed to reach higher redshifts and to probe fully the co-evolution of galaxies and black holes. Cosmic Growth of Black Holes and GalaxiesAbundant evidence indicates that the growth of a supermassive black hole is closely tied to the formation and evolution of the surrounding galaxy. The energy released from accretion onto the black hole affects star formation in the galaxy, probably limiting growth at the high-and low-mass ends, and of course the distribution and angular momentum of matter in the galaxy governs the amount of matter accumulated by the black hole (Silk & Rees 1998;King 2005;Rovilos et al. 2007). Emergent energy from accretion is also a factor in understanding ionization and radiation backgrounds (Hasinger 2000;Lawrence 2001). Understanding the growth history of these black holes is therefore critical to understanding the global evolution of structure in the Universe.Yet the demographics of supermassive black holes remain elusive. The largest samples of quasars and Active Galactic Nuclei (AGN), by which we mean supermassive black holes in a high accretion-rate phase †, have been found through optical selection (e.g., the Sloan Digital Sky Survey quasar sample; Schneider et al. 2002Schneider et al. , 2007, but, at least locally, these are not representative of the larger AGN population. Instead we need surveys less biased against obscured AGN.There are three reasons to suspect that most AGN are obscured by large column densities of gas and dust. First, a large body of evidence suggests that local AGN have geometries that are not spherically symmetric, and that different aspect angles present markedly different observed characteristics; this is referred to as AGN unification (Antonucci 1993;Urry & Padovani 1995). Second, AGN are more common at high redshift (z ∼ 2 − 3), where the average star formation rate is higher and thus it is even more likely that gas and dust surround the galaxy nucleus than at z ∼ 0. Third, and most important, obscured AGN are required to explain the shape of the X-ray "background" radiation.The X-ray "background" is actually the superposition of ind...

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Section: Finding Obscured Agnsupporting

confidence: 70%

supporting

confidence: 70%

Section: Connecting X-ray Optical and Infrared Surveysmentioning

confidence: 99%

mentioning

confidence: 99%

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Supermassive black holes in deep multiwavelength surveys

Urry¹,

Treister²

2011

Black Holes

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“…Lacy et al 2004;Treister et al 2004;Stern et al 2005;Hickox et al 2007Hickox et al , 2009Hickox et al , 2011Stern et al 2012;Hainline et al 2014;DiPompeo et al 2014b;Hickox et al 2014;Lacy et al 2015;DiPompeo et al 2015; that has historically been dominated by optically detected unobscured systems (e.g. Croom et al 2004Croom et al , 2005Richards et al 2006a,b;Myers et al 2007;Croom et al 2009;Ross et al 2009;Shen et al 2009;Bonoli et al 2009;Eftekharzadeh et al 2015).…”

Section: Introductionmentioning

confidence: 99%

A unifying evolutionary framework for infrared-selected obscured and unobscured quasar host haloes

DiPompeo

Hickox

Myers

2016

Mon. Not. R. Astron. Soc.

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Recent measurements of the dark matter halo masses of infrared-selected obscured quasars are in tension -some indicate that obscured quasars have higher halo mass compared to their unobscured counterparts, while others find no difference. The former result is inconsistent with the simplest models of quasar unification that rely solely on viewing angle, while the latter may support such models. Here, using empirical relationships between dark matter halo and supermassive black hole masses, we provide a simple evolutionary picture that naturally explains these findings and is motivated by more sophisticated merger-driven quasar fueling models. The model tracks the growth rate of haloes, with the black hole growing in spurts of quasar activity in order to "catch-up" with the M bh -M stellar -M halo relationship. The first part of the quasar phase is obscured and is followed by an unobscured phase. Depending on the luminosity limit of the sample, driven by observational selection effects, a difference in halo masses may or may not be significant. For high luminosity samples, the difference can be large (a few to 10 times higher masses in obscured quasars), while for lower luminosity samples the halo mass difference is very small, much smaller than current observational constraints. Such a simple model provides a qualitative explanation for the higher mass haloes of obscured quasars, as well as rough quantitative agreement with seemingly disparate results.

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GOODS Discovery of a Significant Population of Obscured AGN

Urry¹,

Treister²

Growing Black Holes: Accretion in a Cosmological Context

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We analysed the optical and infrared properties of X-ray sources in the Great Observatories Origins Deep Survey (GOODS), a deep multiwavelength survey covering 0.1 square degrees in two fields. The HST ACS data are well explained by a unified AGN scheme that postulates roughly 3 times as many obscured as unobscured AGN, as are the spectroscopic and photometric redshift distributions once selection effects are considered. Our model predicts infrared number counts of AGN that agree well with the preliminary Spitzer data, confirming that large numbers of obscured AGN are present in the early Universe (z>1).Comment: To be published in Growing Black Holes, Proc. Garching Conference, June 2004, ed. A. Merloni, A. Nayakshin, R. Sunyaev (Springer-Verlag). 10 pp., 4 fi

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Obscured Active Galactic Nuclei and the X‐Ray, Optical, and Far‐Infrared Number Counts of Active Galactic Nuclei in the GOODS Fields

Cited by 151 publications

References 66 publications

Supermassive black holes in deep multiwavelength surveys

Supermassive black holes in deep multiwavelength surveys

A unifying evolutionary framework for infrared-selected obscured and unobscured quasar host haloes

GOODS Discovery of a Significant Population of Obscured AGN

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