Results 31 to 40 of about 91,098 (240)
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
The Nature of Radio-Intermediate Quasars: What is Radio-Loud and what is Radio-Quiet? [PDF]
, 1996 We have performed quasi-simultaneous radio flux density measurements at 2.7 and 10 GHz for all PG quasars with radio flux densities between 4-200 mJy. We find that a large fraction of these sources are variable, flat-spectrum quasars. This brings the total fraction of flat-spectrum quasars with a ratio between radio and optical flux of R>10 - a value ...
arxiv +1 more source
Exploiting the IRT-THESEUS Capability to Observe Lensed Quasars
Galaxies, 2021 THESEUS is an ESA space based project, which aims to explore the early universe by unveiling a complete census of Gamma-ray Burst (GRB) population in the first billion years.
Lindita Hamolli +3 more
doaj +1 more source
An Empirical Calibration of the Completeness of the SDSS Quasar Survey [PDF]
, 2005 Spectra of nearly 20000 point-like objects to a Galactic reddening corrected magnitude of i=19.1 have been obtained to test the completeness of the SDSS quasar survey.
Avery Meiksin +14 more
core +2 more sources
Relations Between Environments of Quasars and Galaxy Formation [PDF]
Publ.Astron.Soc.Jpn. 55 (2003) 134, 2002 We investigate the environments of quasars such as number distribution of galaxies using a semi-analytic model which includes both galaxy and quasar formations based on the hierarchical clustering scenario. We assume that a supermassive black hole is fueled by accretion of cold gas and that it is a source of quasar activity during a major merger of the
arxiv +1 more source
Exploratory Study of the X-Ray Properties of Quasars With Intrinsic Narrow Absorption Lines [PDF]
, 2008 We have used archival Chandra and XMM-Newton observations of quasars hosting intrinsic narrow UV absorption lines (intrinsic NALs) to carry out an exploratory survey of their X-ray properties.
Blandford R. D. +14 more
core +3 more sources
Imprints of the super-Eddington accretion on the quasar clustering [PDF]
, 2017 Super-Eddington mass accretion has been suggested as an efficient mechanism to grow supermassive black holes (SMBHs). We investigate the imprint left by the radiative efficiency of the super-Eddington accretion process on the clustering of quasars using a new semi-analytic model of galaxy and quasar formation based on large-volume cosmological $N$-body
arxiv +1 more source
The Infrared Traced Star Formation Rates of Associated Absorption Lines Quasars
The Astrophysical JournalSome optically selected quasars exhibit Mg ii- associated absorption lines (AALs), and their origin remains unclear. In this paper, we compile a sample of 1769 quasars, with or without Mg ii AALs, of which 1689 are far-infrared (FIR) detected quasars and
Zhe-Geng Chen +6 more
doaj +1 more source
Journal of Applied Clinical Medical Physics, EarlyView.Abstract Purpose This study aims to evaluate how different gantry angles, breathing rates (BPM), cine image speeds, and tracking algorithms affect beam on/off latency and the subsequent impact on target dose for a 0.35T MR‐Linac with a 6 MV FFF beam.
Mateb Al Khalifa +4 more
wiley +1 more source
Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey [PDF]
, 2007 The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant
Alain Omont +22 more
core +5 more sources