Results 31 to 40 of about 86,681 (283)
A Main Sequence for Quasars [PDF]
Frontiers in Astronomy and Space Sciences, 2018 Invited talk presented at the Padova Conference on "Quasars at all cosmic epochs"; to appear in Frontiers of Astrophysics and Space ...
Marziani, Paola +9 more
openaire +7 more sources
Constraining the anisotropy of the Universe with the X-ray and UV fluxes of quasars
European Physical Journal C: Particles and Fields, 2021 We test the anisotropy in the Finslerian cosmological model with the X-ray and ultraviolet (UV) fluxes of quasars. The 2015 and 2020 compilations of quasars are used in the cosmological constraints.
Dong Zhao, Jun-Qing Xia
doaj +1 more source
The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey [PDF]
, 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
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 < ...
Scott Burles +13 more
openaire +4 more sources
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data II: The Spring Equatorial Stripe [PDF]
, 1999 This is the second paper in a series aimed at finding high-redshift quasars from five-color (u'g'r'i'z') imaging data taken along the Celestial Equator by the Sloan Digital Sky Survey (SDSS) during its commissioning phase.
A. George Pauls +39 more
core +2 more sources
Finding Multiply Lensed and Binary Quasars in the DESI Legacy Imaging Surveys
The Astrophysical Journal Supplement Series, 2023 The time delay between multiple images of strongly lensed quasars is a powerful tool for measuring the Hubble constant ( H _0 ). To achieve H _0 measurements with higher precision and accuracy using the time delay, it is crucial to expand the sample of ...
C. Dawes +6 more
doaj +1 more source
Publications of the Astronomical Society of Australia, 2001 AbstractMicrolens-induced variability in multiple quasars can be used to study two cosmological issues of great interest, the size and brightness profile of quasars on one hand, and the distribution of compact (dark) matter along the line of sight on the other. Here a summary is given of recent theoretical progress as well as observational evidence for
openaire +5 more sources
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 ...
Margaret E. Harding +5 more
openaire +3 more sources
Quasar Luminosity Function at z = 7
The 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 ...
Yoshiki Matsuoka +43 more
doaj +1 more source
On Quasar Masses and Quasar Host Galaxies [PDF]
The Astrophysical Journal, 1998 Accepted for publication in ApJ Letters, 7 pages, aas2pp4 ...
openaire +3 more sources