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More than $200$ quasars have been detected so far at $z > 6$, with only one showing clear signs of strong gravitational lensing. Some studies call for a missing population of lensed high-$z$ quasars, but their existence is still in doubt. A…

Astrophysics of Galaxies · Physics 2022-07-21 Fabio Pacucci , Adi Foord , Lucia Gordon , Abraham Loeb

The recently-finished Edinburgh UVX quasar survey at B < 18 is used together with other complete samples to estimate the shape and evolution of the optical luminosity function in the redshift range 0.3 < z < 2.2. There is a significantly…

Astrophysics · Physics 2009-07-28 Pippa Goldschmidt , Lance Miller

Based on results by recent surveys, the number of bright quasars at redshifts z>3 is being constantly revised upwards. Current consensus is that at bright magnitudes ($M_{1450}\le -27$) the number densities of such sources could have been…

Astrophysics of Galaxies · Physics 2021-05-19 K. Boutsia , A. Grazian , F. Fontanot , E. Giallongo , N. Menci , G. Calderone , S. Cristiani , V. D'Odorico , G. Cupani , F. Guarneri , A. Omizzolo

We present measurements of the mean and scatter of the IGM Lyman-{\alpha} opacity at 4.9 < z < 6.1 along the lines of sight of 62 quasars at z > 5.7, the largest sample assembled at these redshifts to date by a factor of two. The sample…

This is the first paper of a series aiming at investigating galaxy formation and evolution in the giant-void class of the Lemaitre-Tolman-Bondi (LTB) models that best fits current cosmological observations. Here we investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-18 A. Iribarrem , P. Andreani , C. Gruppioni , S. February , M. B. Ribeiro , S. Berta , E. Le Floc'h , B. Magnelli , R. Nordon , P. Popesso , F. Pozzi , L. Riguccini

We present measurements of the size of the quasar proximity zone ($R_p$) for eleven low-luminosity ($-26.16\leq M_{1450}\leq-22.83$) quasars at $z\sim6$, discovered by the Subaru High-$z$ Exploration of Low-Luminosity Quasars project…

We study the observational signatures of a potential population of low-luminosity quasars at high redshifts in a LambdaCDM cosmology. We derive the evolution of the quasar luminosity function at fainter luminosities and higher redshifts…

Astrophysics · Physics 2009-10-30 Zoltan Haiman , Abraham Loeb

We discuss a bias present in the calculation of the global luminosity function (LF) which occurs when analysing faint galaxy samples. This effect exists because of the different spectral energy distributions of galaxies, which are in turn…

Using ~300,000 photometrically classified quasars, by far the largest quasar sample ever used for such analyses, we study the redshift and luminosity evolution of quasar clustering on scales of ~50 kpc/h to ~20 Mpc/h from redshifts of…

Quasars serve as important cosmological probes and constructing accurate luminosity relations for them is essential for their use in cosmology. If the coefficients of quasar's luminosity relation vary with redshift, it could introduce…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-16 Jiayi Wu , Yang Liu , Hongwei Yu , Puxun Wu

[ABRIDGED] I perform a detailed comparison of the shape of the optical luminosity functions as a function of galaxy class and filter, which have been obtained from redshift surveys with an effective depth ranging from z~0.01 to z~0.6. This…

Astrophysics · Physics 2009-11-10 Valerie de Lapparent

Arguably the best hope of understanding the tail end of the reionization of the intergalactic medium (IGM) at redshift z > 6 is through the detection and characterization of the Gunn-Peterson (GP) damping wing absorption of the IGM in…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-25 Roban Hultman Kramer , Zoltan Haiman

We show that the Lyman-alpha optical depth statistics in the proximity regions of quasar spectra depend on the mass of the dark matter halos hosting the quasars. This is owing to both the overdensity around the quasars and the associated…

Astrophysics · Physics 2009-11-13 C. -A. Faucher-Giguere , A. Lidz , M. Zaldarriaga , L. Hernquist

We present a detailed study of the longitudinal proximity effect using a sample of 85 quasars spanning an emission redshift range of $3.5 \leq z_{em} \leq 4.5$ and Lyman continuum luminosity ($L_{912}$) ranging from 1.06$\times 10^{31}$ to…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-26 Priyanka Jalan , Hum Chand , Raghunathan Srianand

We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the…

Astrophysics · Physics 2020-07-28 M. Trenti , M. Stiavelli

Quasar emission lines are sensitive to both the luminosity and shape of the quasars' high energy continuum - primarily in the soft X-ray and the (obscured) extreme ultraviolet. We initiate the first large-scale, multi-line investigation of…

Astrophysics · Physics 2009-10-28 Paul J. Green

We present the discovery of five quasars at z~6 selected from 260 deg^2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the Celestial Equator. The five quasars…

The extensive catalog of $\gamma$-ray selected flat-spectrum radio quasars (FSRQs) produced by \emph{Fermi} during a four-year survey has generated considerable interest in determining their $\gamma$-ray luminosity function (GLF) and its…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-31 Houdun Zeng , Fulvio Melia , Li Zhang

We investigate the precision with which the Lyman-$\alpha$ damping wing signature imprinted on the spectra of high-redshift quasars (QSOs) by the foreground neutral intergalactic medium (IGM) can measure the history of cosmic reionization.…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-19 Timo Kist , Joseph F. Hennawi , Frederick B. Davies

Around 70 $z>6.5$ luminous quasars have been discovered, strongly biased toward the bright end, thus not providing a comprehensive view on quasar abundance beyond cosmic dawn. We present the predicted results of Roman/Rubin high-redshift…

Astrophysics of Galaxies · Physics 2023-08-24 Wei Leong Tee , Xiaohui Fan , Feige Wang , Jinyi Yang , Sangeeta Malhotra , James E. Rhoads
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