Results 11 to 20 of about 113,643 (296)
Gravitationally lensed quasars in Gaia – IV. 150 new lenses, quasar pairs, and projected quasars [PDF]
Monthly Notices of the Royal Astronomical Society, 2022 We report the spectroscopic follow-up of 175 lensed quasar candidates selected using Gaia Data Release 2 observations following Lemon et al. 2019. Systems include 86 confirmed lensed quasars and a further 17 likely lensed quasars based on imaging and ...
C. Lemon +12 more
semanticscholar +5 more sources
Quasar: resource-efficient and QoS-aware cluster management
ACM SIGPLAN Notices, 2014 Cloud computing promises flexibility and high performance for users and high cost-efficiency for operators. Nevertheless, most cloud facilities operate at very low utilization, hurting both cost effectiveness and future scalability. We present Quasar, a cluster management system that increases resource utilization while providing consistently
Christina Delimitrou, Christos Kozyrakis
semanticscholar +2 more sources
The Discovery of a Gravitationally Lensed Quasar at z = 6.51 [PDF]
Astrophysical Journal, 2018 Strong gravitational lensing provides a powerful probe of the physical properties of quasars and their host galaxies. A high fraction of the most luminous high-redshift quasars was predicted to be lensed due to magnification bias.
Bian, Fuyan +19 more
core +4 more sources
Quasar Clustering and the Lifetime of Quasars [PDF]
The Astrophysical Journal, 2000 Although the population of luminous quasars rises and falls over a period of 10^9 years, the typical lifetime of individual quasars is uncertain by several orders of magnitude.
Baugh C. M. +17 more
core +4 more sources
A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity [PDF]
, 2007 (Abridged) We develop a model for the cosmological role of mergers in the evolution of starbursts, quasars, and spheroidal galaxies. Combining halo mass functions (MFs) with empirical halo occupation models, we calculate where major galaxy-galaxy mergers
Athanassoula E. +21 more
core +2 more sources
Quaia, the Gaia-unWISE Quasar Catalog: An All-sky Spectroscopic Quasar Sample [PDF]
Astrophysical Journal, 2023 We present a new, all-sky quasar catalog, Quaia, that samples the largest comoving volume of any existing spectroscopic quasar sample. The catalog draws on the 6,649,162 quasar candidates identified by the Gaia mission that have redshift estimates from ...
Kate Storey-Fisher +6 more
semanticscholar +1 more source
Quasar Luminosity Function at z = 7 [PDF]
Astrophysical Journal Letters, 2023 We present the quasar luminosity function (LF) at z = 7, measured with 35 spectroscopically confirmed quasars at 6.55 < z < 7.15. The sample of 22 quasars from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, combined with 13 ...
Y. Matsuoka +43 more
semanticscholar +1 more source
A Luminous Quasar at Redshift 7.642 [PDF]
, 2021 Distant quasars are unique tracers to study the formation of the earliest supermassive black holes (SMBHs) and the history of cosmic reionization. Despite extensive efforts, only two quasars have been found at z ≥ 7.5, due to a combination of their low ...
Feige Wang +22 more
semanticscholar +1 more source
A Catalog of Quasar Properties from Sloan Digital Sky Survey Data Release 16 [PDF]
Astrophysical Journal Supplement Series, 2022 We present a catalog of continuum and emission-line properties for 750,414 broad-line quasars included in the Sloan Digital Sky Survey Data Release 16 quasar catalog (DR16Q), measured from optical spectroscopy.
Qiaoya Wu, Yue Shen
semanticscholar +1 more source
Detection of stellar light from quasar host galaxies at redshifts above 6 [PDF]
Nature, 2022 The detection of starlight from the host galaxies of quasars during the reionization epoch ( z > 6) has been elusive, even with deep Hubble Space Telescope observations^ 1 , 2 .
Xuheng Ding +43 more
semanticscholar +1 more source