Results 151 to 160 of about 117,210 (326)
A quasar companion to the puzzling quasar SDSS J0927+2943 [PDF]
Astronomy and Astrophysics, 2010 4 pages, 3 figures.
M. Barattini +4 more
openaire +5 more sources
On the Gas Content and Efficiency of AGN Feedback in Low-redshift Quasars [PDF]
, 2018 The interstellar medium is crucial to understanding the physics of active galaxies and the coevolution between supermassive black holes and their host galaxies. However, direct gas measurements are limited by sensitivity and other uncertainties.
J. Shangguan, L. Ho, Yanxia Xie
semanticscholar +1 more source
The Astrophysical JournalThe search for dual supermassive black holes (SMBHs) is of immense interest in modern astrophysics. Galaxy mergers may fuel and produce SMBH pairs. Actively accreting SMBH pairs are observed as dual quasars, which are vital probes of SMBH growth.
Yuzo Ishikawa +12 more
doaj +1 more source
On the Fraction of X-ray Weak Quasars from the Sloan Digital Sky Survey [PDF]
arXiv, 2020 We investigate systematically the X-ray emission from type 1 quasars using a sample of 1825 Sloan Digital Sky Survey (SDSS) non-broad absorption line (non-BAL) quasars with Chandra archival observations. A significant correlation is found between the X-ray-to-optical power-law slope parameter ($\alpha_{\rm OX}$) and the 2500 $\r{A}$ monochromatic ...
arxiv
Optical and radio properties of giant radio quasars: Central black hole characteristics
, 2012 We analysed the optical and radio properties of lobe-dominated giant-sized (> 0.72 Mpc) radio quasars and compared the results with those derived for a sample of smaller radio sources to determine whether the large size of some extragalactic radio ...
Jamrozy, M., Kuźmicz, A.
core +1 more source
Journal of Applied Clinical Medical Physics, Volume 26, Issue 4, April 2025.Abstract Purpose This work describes a single institution experience of commissioning a real‐time target tracking and beam control system, known as comprehensive motion management, for a 1.5 T Elekta MR‐Linac. Methods Anatomical tracking and radiation beam control were tested using the MRI4D Quasar motion phantom.
Blake R Smith +2 more
wiley +1 more source
New Astronomy Reviews, 2006 8 pages, 6 figures, review article with C. Impey at the conference on "QSO Host Galaxies: Evolution and Environment", Aug. 29-Sep.
Hans-Walter Rix +7 more
openaire +3 more sources
Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ∼ 6 Quasars. II. A Sample of 19 Quasars [PDF]
, 2005 We study the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate-resolution spectra of a sample of 19 quasars at 5.74 < zem < 6.42 discovered in the Sloan Digital Sky Survey.
Xiaohui Fan +11 more
semanticscholar +1 more source
Infrared properties of serendipitous X-ray quasars [PDF]
, 1982 Near infrared measurements were obtained of 30 quasars originally found serendipitously as X-ray sources in fields of other objects. The observations show that the infrared characteristics of these quasars do not differ significantly from those of ...
Chanan, G. A. +4 more
core +1 more source
, 2012 Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with $i$-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from
Chen-Wei Yang +33 more
core +1 more source