Results 31 to 40 of about 94,086 (264)
Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample [PDF]
, 2002 We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their non-stellar colors in "ugriz" broad-band photometry, and by matching unresolved sources to the ...
Adam Boucher +24 more
core +2 more sources
Tension with the flat ΛCDM model from a high-redshift Hubble diagram of supernovae, quasars, and gamma-ray bursts [PDF]
Astronomy & Astrophysics, 2019 In the current framework, the standard parametrization of our Universe is the so-called Lambda cold dark matter (ΛCDM) model. Recently, a ∼4σ tension with the ΛCDM model was shown to exist via a model-independent parametrization of a Hubble diagram of ...
E. Lusso +6 more
semanticscholar +1 more source
Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey [PDF]
, 2007 The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant
Alain Omont +22 more
core +6 more sources
An ALMA [C ii] Survey of 27 Quasars at z > 5.94 [PDF]
Astrophysical Journal, 2018 We present a survey of the [C ii] 158 μm line and underlying far-infrared (FIR) dust continuum emission in a sample of 27 quasars using the Atacama Large Millimeter Array (ALMA) at resolution.
R. Decarli +13 more
semanticscholar +1 more source
Astronomy & Astrophysics, 2020 Context. In recent years, Lyα nebulae have been routinely detected around high redshift, radio-quiet quasars thanks to the advent of the highly sensitive integral field spectrographs. Constraining the physical properties of the Lyα nebulae is crucial for
A. Travascio +13 more
semanticscholar +1 more source
Quantitative Constraints on the Reionization History from the IGM Damping Wing Signature in Two Quasars at z > 7 [PDF]
Astrophysical Journal, 2018 During reionization, neutral hydrogen in the intergalactic medium (IGM) imprints a damping wing absorption feature on the spectrum of high-redshift quasars.
F. Davies +12 more
semanticscholar +1 more source
Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths [PDF]
, 2016 The sub-population of quasars reddened by intrinsic or intervening clouds of dust are known to be underrepresented in optical quasar surveys. By defining a complete parent sample of the brightest and spatially unresolved quasars in the COSMOS field, we ...
Fynbo, J. P. U. +10 more
core +2 more sources
Symposium - International Astronomical Union, 1994 I review recent results for quasars and discuss how they are related to activity in galaxies. Topics included are studies of quasar host galaxies with HST; searches for quasars in the Hubble Deep Field; evolution of the quasar luminosity function; news highlights from astro-ph; and current observational research problems and their relation to ...
openaire +2 more sources
The Astrophysical Journal, 2023 We present, for the first time, dark matter halo (DMH) mass measurement of quasars at z ∼ 6 based on a clustering analysis of 107 quasars. Spectroscopically identified quasars are homogeneously extracted from the Hyper Suprime-Cam Strategic Survey ...
Junya Arita +12 more
doaj +1 more source
Exploratory Study of the X-Ray Properties of Quasars With Intrinsic Narrow Absorption Lines [PDF]
, 2008 We have used archival Chandra and XMM-Newton observations of quasars hosting intrinsic narrow UV absorption lines (intrinsic NALs) to carry out an exploratory survey of their X-ray properties.
Blandford R. D. +14 more
core +3 more sources