The Luminosity Function of z&gt;4 Quasars from the Second Palomar Sky Survey

Kennefick, Julia; Djorgovski, S. G.; Carvalho, R. R. de

doi:10.1086/117711

Cited by 141 publications

(132 citation statements)

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“…The functional dependence on redshift is in the break luminosity L Ã indicating pure luminosity evolution. At z s 5 3 the break luminosity evolves as a power law in redshift, and the number counts increase with redshift; higher redshift surveys indicate that there is a decline in the space density of bright quasars beyond z s $ 3 (Warren, Hewett, & Osmer 1994;Schmidt, Schneider, & Gunn 1995;Kennefick, Djorgovski, & de Carvalho 1995). Madau et al (1999) suggested an evolution of L Ã of the form…”

Section: Quasar Luminosity Functionmentioning

confidence: 99%

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

Wyithe

Loeb

2002

ApJ

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We predict the effects of gravitational lensing on the color-selected flux-limited samples of z s $ 4:3 and z s e5:8 quasars, recently published by the Sloan Digital Sky Survey (SDSS). Our main findings are the following: (1) The lensing probability should be 1-2 orders of magnitude higher than for conventional surveys. The expected fraction of multiply imaged quasars is highly sensitive to redshift and the uncertain slope of the bright end of the luminosity function, h . For h ¼ 2:58 (3.43) we find that at z s $ 4:3 and i Ã < 20:0 the fraction is $4% (13%), while at z s $ 6 and z Ã < 20:2 the fraction is $7% (30%). (2) The distribution of magnifications is heavily skewed; sources having the redshift and luminosity of the SDSS z s e5:8 quasars acquire median magnifications of medðl obs Þ $ 1:1 1:3 and mean magnifications of hl obs i $ 5 50. Estimates of the quasar luminosity density at high redshift must therefore filter out gravitationally lensed sources. (3) The flux in the Gunn-Peterson trough of the highest redshift (z s ¼ 6:28) quasar is known to be f < 3 Â 10 À19 ergs s À1 cm À2 Å À1 . Should this quasar be multiply imaged, we estimate a 40% chance that light from the lens galaxy would have contaminated the same part of the quasar spectrum with a higher flux. Hence, spectroscopic studies of the epoch of reionization need to account for the possibility that a lens galaxy, which boosts the quasar flux, also contaminates the Gunn-Peterson trough. (4) Microlensing by stars should result in $ 1 3 of multiply imaged quasars in the z s e5:8 catalog varying by more than 0.5 mag over the next decade. The median emission-line equivalent width of multiply imaged quasars would be lowered by $20% with respect to the intrinsic value because of differential magnification of the continuum and emission-line regions.

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Section: Quasar Luminosity Functionmentioning

confidence: 99%

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

Wyithe

Loeb

2002

ApJ

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“…In this paper, we take a further step by jointly considering the evolution of the BH-halo relation and the BH mass function, as constrained by the observed AGN luminosity function and clustering. We examine constraints on the host halos, duty cycles, radiative efficiencies, and mean Eddington ratios of massive BHs at z > 3, imposed by the clustering measurements of S07 and by a variety of measurements of the quasar luminosity function at 3 z 6 (e.g., Kennefick et al 1995;Pei 1995;Fan et al 2001Fan et al , 2004Barger et al 2003;Wolf et al 2003;Hunt et al 2004;Barger & Cowie 2005;La Franca et al 2005;Nandra et al 2005;Cool et al 2006;Richards et al 2006a;Bongiorno et al 2007;Fontanot et al 2007;Shankar & Mathur 2007;Silverman et al 2008;Shankar et al 2010;F. Shankar et al 2010, in preparation).…”

Section: Introductionmentioning

confidence: 99%

On the Radiative Efficiencies, Eddington Ratios, and Duty Cycles of Luminous High-Redshift Quasars

Shankar¹,

Crocce²,

Miralda-Escudé³

et al. 2010

ApJ

132

184

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We investigate the characteristic radiative efficiency , Eddington ratio λ, and duty cycle P 0 of high-redshift active galactic nuclei (AGNs), drawing on measurements of the AGN luminosity function at z = 3-6 and, especially, on recent measurements of quasar clustering at z = 3-4.5 from the Sloan Digital Sky Survey. The free parameters of our models are , λ, and the normalization, scatter, and redshift evolution of the relation between black hole (BH) mass M BH and halo virial velocity V vir . We compute the luminosity function from the implied growth of the BH mass function and the quasar correlation length from the bias of the host halos. We test our adopted formulae for the halo mass function and halo bias against measurements from the large N-body simulation developed by the MICE collaboration. The strong clustering of AGNs observed at z = 3 and, especially, at z = 4 implies that massive BHs reside in rare, massive dark matter halos. Reproducing the observed luminosity function then requires high efficiency and/or low Eddington ratio λ, with a lower limit (based on 2σ agreement with the measured z = 4 correlation length)0.7λ/(1 + 0.7λ), implying 0.17 for λ > 0.25. Successful models predict high duty cycles, P 0 ∼ 0.2, 0.5, and 0.9 at z = 3.1, 4.5, and 6, respectively, and they require that the fraction of halo baryons locked in the central BH is much larger than the locally observed value. The rapid drop in the abundance of the massive and rare host halos at z > 7 implies a proportionally rapid decline in the number density of luminous quasars, much stronger than simple extrapolations of the z = 3-6 luminosity function would predict. For example, our most successful model predicts that the highest redshift quasar in the sky with true bolometric luminosity L > 10 47.5 erg s −1 should be at z ∼ 7.5, and that all quasars with higher apparent luminosities would have to be magnified by lensing.

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“…Many studies have been conducted and many results obtained in the past few years to constrain the optical luminosity function of type-1 AGN at both low (Boyle et al 1988;Hewett et al 1991;Pei 1995;Boyle et al 2000;Croom et al 2004) and high redshift (Warren et al 1994;Kennefick et al 1995;Schmidt et al 1995;Fan et al 2001;Wolf et al 2003;Hunt et al 2004;Bongiorno et al 2007;Croom et al 2009). In contrast, there are not many type-2 AGN samples available in the literature and consequently very few studies of their evolution have been conducted.…”

Section: Introductionmentioning

confidence: 99%

The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS$^{\rm,}$

Bongiorno

Mignoli

Zamorani

et al. 2010

A&A

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Aims. We present a catalog of 213 type-2 AGN selected from the zCOSMOS survey. The selected sample covers a wide redshift range (0.15 < z < 0.92) and is deeper than any other previous study, encompassing the luminosity range 10 5.5 L < L [OIII] < 10 9.1 L . We explore the intrinsic properties of these AGN and the relation to their X-ray emission (derived from the XMM-COSMOS observations). We study their evolution Results. Combining our sample with one drawn from SDSS, we found that the best description of the evolution of type-2 AGN is a luminositydependent density evolution model. Moreover, using the type-1 AGN LF we were able to constrain the fraction of type-2 AGN to the total (type-1 + type-2) AGN population. We found that the type-2 fraction decreases with luminosity, in agreement with the most recent results, and shows signs of a slight increase with redshift. However, the trend with luminosity is visible only after combining the SDSS+zCOSMOS samples. From the COSMOS data points alone, the type-2 fraction seems to be quite constant with luminosity.

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The Luminosity Function of z>4 Quasars from the Second Palomar Sky Survey

Cited by 141 publications

References 0 publications

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

On the Radiative Efficiencies, Eddington Ratios, and Duty Cycles of Luminous High-Redshift Quasars

The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS$^{\rm,}$

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