Quasars Probing Quasars. I. Optically Thick Absorbers near Luminous Quasars [PDF]
The 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
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A Test of the Cosmological Principle with Quasars [PDF]
, 2020 We study the large-scale anisotropy of the universe by measuring the dipole in the angular distribution of a flux-limited, all-sky sample of 1.36 million quasars observed by the Wide-field Infrared Survey Explorer (WISE).
N. Secrest +5 more
semanticscholar +1 more source
Quasars as standard candles [PDF]
Astronomy & Astrophysics, 2020 We present a new catalogue of ∼2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM–Newton. The sample can be used to investigate the non-linear relation between the ultraviolet (UV) and X-ray ...
E. Lusso +17 more
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Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei [PDF]
, 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
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Baryon acoustic oscillations from the cross-correlation of Lyα absorption and quasars in eBOSS DR14 [PDF]
Astronomy & 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
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The X-SHOOTER/ALMA Sample of Quasars in the Epoch of Reionization. I. NIR Spectral Modeling, Iron Enrichment, and Broad Emission Line Properties [PDF]
Astrophysical Journal, 2020 We present X-SHOOTER near-IR spectroscopy of a large sample of 38 luminous (M1450 = −29.0 to −24.4) quasars at 5.78 < z < 7.54, which have complementary [C ii]158μm observations from ALMA.
J. Schindler +17 more
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Do Quasars Lens Quasars? [PDF]
The Astrophysical Journal, 1997 If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be $\sim10^{12}M_{\sun}$ and the sum of all such quasar lenses would have to contain $\sim0.005$ times the closure density of the Universe.
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Two Close Separation Quasar-Quasar Pairs in the Large Bright Quasar Survey [PDF]
The Astronomical Journal, 1998 Accepted for publication in the Astronomical Journal, Paper, 4 Figures + 1 ...
Hewett, Paul C. +3 more
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Spectral Properties of Quasars from Sloan Digital Sky Survey Data Release 14: The Catalog [PDF]
Astrophysical Journal Supplement Series, 2019 We present measurements of the spectral properties for a total of 526,265 quasars, out of which 63% have a continuum signal-to-noise ratio > 3 pixel−1, selected from the fourteenth data release of the Sloan Digital Sky Survey (SDSS-DR14) quasar catalog ...
S. Rakshit, C. .. Stalin, J. Kotilainen
semanticscholar +1 more source
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
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