Related papers: A Constraint on Quasar Clustering at z=5 from a Bi…

We report the discovery of a pair of z = 4.25 quasars with a separation of 33 arcseconds. The brighter of the two objects was identified as a high-redshift quasar candidate from Sloan Digital Sky Survey multicolor imaging data, and the…

We report a discovery of a quasar at z = 4.96 +- 0.03 within a few Mpc of the quasar SDSS 0338+0021 at z = 5.02 +- 0.02. The newly found quasar has the SDSS i and z magnitudes of ~ 21.2, and an estimated absolute magnitude M_B ~ -25.2. The…

(Abridged) We study the two-point correlation function of a uniformly selected sample of 4,426 luminous optical quasars with redshift $2.9 \le z\le 5.4$ selected over 4041 deg$^2$ from the Fifth Data Release of the Sloan Digital Sky Survey.…

Quasars are effective tracers of the large-scale distribution of galaxies at high redshift thanks to their high luminosity and dedicated surveys. Previous studies have shown that quasars exhibit a bias similar to that of rich groups,…

The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high redshift binary quasars.…

Binary quasars are extremely rare objects, used to investigate clustering on very small scales at different redshifts. The cases where the two quasar components are gravitationally bound, known as physical binary quasars, can also exhibit…

We present measurements of the quasar two-point correlation function, \xi_{Q}, over the redshift range z=0.3-2.2 based upon data from the SDSS. Using a homogeneous sample of 30,239 quasars with spectroscopic redshifts from the DR5 Quasar…

We examine the clustering of galaxies around a sample of 20 luminous low redshift (z<0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope. The HST resolution makes possible galaxy identification brighter than…

We test the hypothesis whether high redshift QSOs would preferentially appear in small groups or pairs, and if they are associated with massive, young clusters. We carried out a photometric search for \Ly emitters on scales $\lesssim 10…

We present spectroscopy of binary quasar candidates selected from Data Release 4 of the Sloan Digital Sky Survey (SDSS DR4) using Kernel Density Estimation (KDE). We present 27 new sets of observations, 10 of which are binary quasars,…

We present measurements of the small-scale (0.1<~ r <~ 1 Mpc/h) quasar two-point correlation function at z>2.9, for a flux-limited (i<21) sample of 15 binary quasars compiled by Hennawi et al. (2009). The amplitude of the small-scale…

We report the discovery of a close quasar pair candidate at $z=5.66$, J2037--4537. J2037--4537 is resolved into two quasar images at the same redshift in ground-based observations. Followup spectroscopy shows significant differences in both…

The evolution of quasar clustering is investigated with a new sample of 388 quasars with 0.3<z<=2.2, B<=20.5 and Mb<-23, selected over an area of 24.6 sq. deg. in the South Galactic Pole. Assuming a two-point correlation function of the…

We investigate the spatial clustering of galaxies around quasars at redshifts from 0.6 to 1.2 using the photometric data from Sloan Digital Sky Survey (SDSS) Stripe 82. The quasar and galaxy cross-correlation functions are measured through…

Large-scale surveys over the last years have revealed about 300 QSOs at redshift above 6. Follow-up observations identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas…

We report the discovery of two quasars at a redshift of $z$ = 6.05, in the process of merging. They were serendipitously discovered from the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program…

The quest for structure indicators at earlier and earlier times in the evolution of the universe has led to the search for objects with ever higher redshifts. The Palomar Transit Grism Survey has produced a large sample of high redshift…

We present initial results from the first systematic survey of luminous $z\sim 5.5$ quasars. Quasars at $z \sim$ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution and the…

We study quasar clustering on small scales, modeling clustering amplitudes using halo-driven dark matter descriptions. From 91 pairs on scales <35 kpc/h, we detect only a slight excess in quasar clustering over our best-fit large-scale…

Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only few quasars have been reported at $z > 6.5$ ($<$800 Myr after the Big Bang). In this work,…