Results 21 to 30 of about 24,041 (212)
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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Localization accuracy of 6-second CBCT for lung IGRT with various breathing patterns. [PDF]
J Appl Clin Med PhysAbstract Purpose The 6‐second cone beam computed tomography (CBCT) acquisition of the Ethos HyperSight (Varian Medical Systems, Inc. Palo Alto, CA, USA) on‐board imaging system offers benefits, but could be too fast to accurately capture an average target position in a free‐breathing lung cancer patient. This study aimed to ascertain whether a 6‐second
Koo J +5 more
europepmc +2 more sources
The Astrophysical Journal Letters, 2023 We report the discovery of COOL J0335−1927, a quasar at z = 3.27 lensed into three images with a maximum separation of 23.″3 by a galaxy cluster at z = 0.4178. To date, this is the highest redshift wide-separation lensed quasar known.
Kate Napier +20 more
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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
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Autosomal Dominant Leukodystrophy: A Disease of the Nuclear Lamina
Frontiers in Cell and Developmental Biology, 2019 The nuclear lamina is a fibrous meshwork of proteins found adjacent to the inner nuclear membrane that plays a critical role in the maintenance of nuclear architecture.
Quasar S. Padiath
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A slitless spectroscopic survey for quasars near quasars [PDF]
Astronomy & Astrophysics, 2008 18 pages, 16 figures, accepted by A&A, includes Table 2 from online material, full paper with appendices containing additional figures and tables available at http://www.aip.de/People/gworseck/qnqpaper/qnqpaper_final ...
Lutz Wisotzki +2 more
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Circum-Galactic Medium in the Halo of Quasars
Frontiers in Astronomy and Space Sciences, 2017 The properties of circum-galactic gas in the halo of quasar host galaxies are investigated analyzing Mg II 2800 and C IV 1540 absorption-line systems along the line of sight close to quasars.
Riccardo Ottolina +6 more
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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
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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 ...
Margaret E. Harding +5 more
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Science, 1986 In the quarter century since the first optical identification of a "radio star" (3C 48), astronomers have come to general agreement that the underlying quasar energy source is accretion onto a massive black hole. There is much less agreement on the detailed physics of the processes by which this energy is converted to the forms observed, but this has ...
Trimble, Virginia, Woltjer, Lodewijk
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