Results 21 to 30 of about 110,927 (295)

Finding Rare Quasars: VLA Snapshot Continuum Survey of FRI Quasar Candidates Selected from the LOFAR Two-Metre Sky Survey (LoTSS)

open access: yesGalaxies, 2021
The radiative and jet power in active galactic nuclei is generated by accretion of material on to supermassive galactic-centre black holes. For quasars, where the radiative power is by definition very high, objects with high radio luminosities form 10 ...
Gülay Gürkan   +5 more
doaj   +1 more source

Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei [PDF]

open access: yes, 1999
Correlated variations in the line and continuum emission from active galactic nuclei (AGNs) can be used to determine the size and geometry of the broad emission-line regions (BLRs).
S. Kaspi   +5 more
semanticscholar   +1 more source

Baryon acoustic oscillations from the cross-correlation of Lyα absorption and quasars in eBOSS DR14 [PDF]

open access: yesAstronomy & Astrophysics, 2019
We present a measurement of the baryon acoustic oscillation (BAO) scale at redshift z = 2.35 from the three-dimensional correlation of Lyman-α (Lyα) forest absorption and quasars. The study uses 266 590 quasars in the redshift range 1.77 <  z <  3.5 from
M. Blomqvist   +17 more
semanticscholar   +1 more source

A HUBBLE DIAGRAM FOR QUASARS [PDF]

open access: yesThe Astrophysical Journal, 2015
ApJ ...
Lusso E., RISALITI, GUIDO
openaire   +3 more sources

A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey [PDF]

open access: yes, 2008
We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \AA) at 1.7 < z < 4.0 selected from the Sloan Digital Sky Survey (SDSS) Fifth Data Release.
Fan, Xiaohui   +2 more
core   +2 more sources

Quasars Probing Quasars. I. Optically Thick Absorbers near Luminous Quasars [PDF]

open access: yesThe Astrophysical Journal, 2006
With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We search 149 moderate resolution background quasar spectra, from Gemini, Keck, the MMT, and the SDSS to survey Lyman Limit Systems (LLSs) and Damped Ly-alpha systems (DLAs) in the vicinity of 1.8 < ...
Hennawi, Joseph F.   +13 more
openaire   +2 more sources

The Small-Scale Environment of Quasars [PDF]

open access: yes, 2006
Where do quasars reside? Are quasars located in environments similar to those of typical L* galaxies, and, if not, how do they differ? An answer to this question will help shed light on the triggering process of quasar activity.
Bahcall, Neta   +3 more
core   +1 more source

Two Close Separation Quasar-Quasar Pairs in the Large Bright Quasar Survey [PDF]

open access: yesThe Astronomical Journal, 1998
Accepted for publication in the Astronomical Journal, Paper, 4 Figures + 1 ...
Hewett, Paul C.   +3 more
openaire   +2 more sources

The Pan-STARRS1 z > 5.6 Quasar Survey. II. Discovery of 55 Quasars at 5.6 < z < 6.5

open access: yesThe Astrophysical Journal Supplement Series, 2023
The identification of bright quasars at z ≳ 6 enables detailed studies of supermassive black holes, massive galaxies, structure formation, and the state of the intergalactic medium within the first billion years after the Big Bang.
Eduardo Bañados   +22 more
doaj   +1 more source

The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey [PDF]

open access: yes, 2010
We have compiled a sample of 14 of the optically brightest radio-quiet quasars ($m_{i}$~$\le$~17.5 and $z$~$\ge$~1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-BALs present in their spectra.
Arav   +37 more
core   +2 more sources

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