Results 71 to 80 of about 116,814 (325)
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
openaire +4 more sources
The quasar luminosity function at $z\sim5$ via deep learning and Bayesian information criterion [PDF]
, 2022 Understanding the faint end of quasar luminosity function at a high redshift is important since the number density of faint quasars is a critical element in constraining ultraviolet (UV) photon budgets for ionizing the intergalactic medium (IGM) in the early universe.
arxiv +1 more source
Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths [PDF]
, 2016 The sub-population of quasars reddened by intrinsic or intervening clouds of dust are known to be underrepresented in optical quasar surveys. By defining a complete parent sample of the brightest and spatially unresolved quasars in the COSMOS field, we ...
Fynbo, J. P. U. +10 more
core +1 more source
The Astrophysical Journal, 2023 We explore reprocessing models for a sample of 17 hypervariable quasars, taken from the Sloan Digital Sky Survey Reverberation Mapping project, which all show coordinated optical luminosity hypervariability with amplitudes of factors ≳2 between 2014 and ...
Tatsuya Akiba +7 more
doaj +1 more source
Proceedings of the International Astronomical Union, 2014 AbstractAlthough the extragalactic nature of 3C 48 and other quasi stellar radio sources was discussed as early as 1960 by John Bolton and others, it was rejected largely because of preconceived ideas about what appeared to be unrealistically high radio and optical luminosities.
openaire +3 more sources
The Sloan Digital Sky Survey Quasar Lens Search. II. Statistical lens sample from the third data release [PDF]
, 2007 We report the first results of our systematic search for strongly lensed quasars using the spectroscopically confirmed quasars in the Sloan Digital Sky Survey (SDSS).
Anderson, Scott F. +33 more
core +3 more sources
A catalogue of quasars and active nuclei: 12th edition
, 1998 Aims. This catalogue is aimed at presenting a compilation of all known AGN in a compact and convenient form and we hope that it will be useful to all workers in this field. Methods.
M. Véron-Cetty, P. Véron
semanticscholar +1 more source
Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). X. Discovery of 35 Quasars and Luminous Galaxies at 5.7 ≤ z ≤ 7.0 [PDF]
Astrophysical Journal, 2019 We report the discovery of 28 quasars and 7 luminous galaxies at 5.7 ≤ z ≤ 7.0. This is the tenth in a series of papers from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which exploits the deep multiband imaging data ...
Y. Matsuoka +46 more
semanticscholar +1 more source
On the Formation of the First Quasars [PDF]
Publications of the Astronomical Society of Australia, 2017 AbstractObservations of the most luminous quasars at redshiftz> 6 reveal the existence of numerous supermasssive black holes (>199M⊙) already in place about 12 billion years ago. In addition, the interstellar medium of the galaxies hosting these black holes are observed to be chemically mature systems, with metallicities (Z> Z⊙) and dust ...
Rosa, Valiante +3 more
openaire +5 more sources
Obscuration by Gas and Dust in Luminous Quasars [PDF]
, 2014 We explore the connection between absorption by neutral gas and extinction by dust in mid-infrared (IR) selected luminous quasars. We use a sample of 33 quasars at redshifts 0.7 < z < 3 in the 9 deg^2 Bo\"otes multiwavelength survey field that are ...
Brodwin, Mark +3 more
core +3 more sources