Are Two z ∼ 6 Quasars Gravitationally Lensed? ∗

  title={Are Two z ∼ 6 Quasars Gravitationally Lensed? ∗},
  author={Sanae F. Yamada and Yasuhiro Shioya and Yoshiaki Taniguchi and Takashi Murayama and Masaru Ajiki and Tohru Nagao and Shinobu S. Fujita and Kazuyoshi Umeda and Yutaka Komiyama and Hiroshi Karoji and Hiroyasu Ando and Masanori Iye and Nobunari Kashikawa and Keiichi Kodaira},
  journal={Publications of the Astronomical Society of Japan},
Several high-z (z > 5.7) quasars have been found during the course of Sloan Digital Sky Survey. The presence of such very high-z quasars is expected to put constraints on early structure formation. On one hand, it is suggested that these most luminous objects at high redshift are biased toward highly magnified objects by gravitational lensing. To clarify the effect of gravitational lensing on high-z quasars, we began an imaging survey of intervening lensing galaxies. Indeed, our previous… Expand

Figures and Tables from this paper

A Snapshot Survey for Gravitational Lenses among z >= 4.0 Quasars
Over the last few years, the Sloan Digital Sky Survey (SDSS) has discovered several hundred quasars with redshift between 4.0 and 6.4. Including the effects of magnification bias, one expects aExpand
Imaging of sdss z > 6 quasar fields : Gravitational lensing, companion galaxies, and the host dark matter halos
We have undertaken deep optical imaging observations of three 6.2 < z < 6.5 quasar fields in the i' and z' filters. These data are used to search for foreground galaxies that are gravitationallyExpand
The SUBARU Deep Field Project: Lymanα Emitters at a Redshift of 6.6
We present new results of a deep optical imaging survey using a narrow band filter (NB921) centered at λ = 9196 u A together with B, V, R, i � ,a ndzbroadband filters in the sky area of the SubaruExpand
Study of Possible Local Quasars I: The First Sample
This study provides new arguments for the existence of local quasars, i.e. quasars in the vicinity of low redshift galaxies. Local quasars are probably ejected from respective parent galaxy. TheExpand
High-resolution radio imaging of the most distant radio quasar SDSS J0836+0054
We observed SDSS J0836+0054, the most distant radio-loud quasar known at present ($z=5.774$) with the European Very Long Baseline Interferometry (VLBI) Network at the 5 GHz frequency on 2003 NovemberExpand
Pending Problems in QSOs
Quasars (Quasi Stellar Objects, abbreviated as QSOs) are still nowadays, close to half a century after their discovery, objects which are not completely understood. In this brief review a descriptionExpand
Scientific highlights.
A big news in the FY 2003 is the allocation of the 8-year ALMA construction budget for NAOJ by the Government and one of the important concepts of ALMA is a big jump in spatial resolution to achieve 0.01 arc-sec in sub-millimeter wavelength region. Expand


A Survey of z > 5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at z > 6
We present the discovery of three new quasars at z > 6 in ~ 1300 deg2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z = 6.43), J104845.05+463718.3 (z = 6.23), and J163033.90+401209.6Expand
Constraining the Redshift z=6 Quasar Luminosity Function Using Gravitational Lensing
Recent discoveries by the Sloan Digital Sky Survey (SDSS) of four bright redshift z=6 quasars could constrain the mechanism by which the supermassive black holes powering these sources are assembled.Expand
Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars
We predict the effects of gravitational lensing on the color-selected flux-limited samples of zs ~ 4.3 and zs 5.8 quasars, recently published by the Sloan Digital Sky Survey (SDSS). Our main findingsExpand
A Survey of z > 5.8 quasars in the Sloan Digital Sky Survey I: Discovery of three new quasars and the spatial density of luminous quasars at z ~ 6
We present the results from a survey of i-dropout objects selected from ~1550 deg2 of multicolor imaging data from the Sloan Digital Sky Survey to search for luminous quasars at z 5.8. Objects withExpand
The discovery of a luminous z = 5.80 quasar from the sloan digital sky survey
We present observations of SDSSp J104433.04-012502.2, a luminous quasar at z = 5.80 discovered from Sloan Digital Sky Survey (SDSS) multicolor imaging data. This object was selected as an i'-bandExpand
What Is the Highest Plausible Redshift of Luminous Quasars
The recent discoveries of luminous quasars at high redshifts imply that black holes more massive than a few billion solar masses were already assembled when the universe was less than a billion yearsExpand
High-Redshift Galaxies: Their Predicted Size and Surface Brightness Distributions and Their Gravitational Lensing Probability
Direct observations of the first generation of luminous objects will likely become feasible over the next decade. The advent of the Next Generation Space Telescope (NGST) will allow imaging ofExpand
Evidence for reionization at z ∼ 6: Detection of a gunn-peterson trough in a z = 6.28 quasar
We present moderate-resolution Keck spectroscopy of quasars at z = 5.82, 5.99, and 6.28, discovered by the Sloan Digital Sky Survey (SDSS). We find that the Ly? absorption in the spectra of theseExpand
The discovery of a very narrow line star-forming object at a redshift of 5.66
We report on the discovery of a very narrow line star-forming object beyond a redshift of 5. Using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru Telescope together with a narrow-passbandExpand
Magnification of light from many distant quasars by gravitational lenses
Up to one-third of known quasars with z ≈ 6 will have had their observed flux magnified by a factor of ten or more, as a consequence of gravitational lensing by galaxies along the line of sight. Expand