Results 101 to 110 of about 81,623 (245)
A Physical Model for the Origin of Quasar Lifetimes
, 2005 We propose a model of quasar lifetimes in which observational quasar lifetimes and an intrinsic lifetime of rapid accretion are strongly distinguished by the physics of obscuration by surrounding gas and dust.
Bouchet P. +9 more
core +1 more source
Tunable-filter imaging of quasar fields at z~1. I. A cluster around MRC B0450-221 [PDF]
, 2000 Using a combination of multicolour broad- and narrow-band imaging techniques and follow-up spectroscopy, we have detected an overdensity of galaxies in the field of quasar MRC B0450-221, whose properties are consistent with a cluster at the quasar ...
Baker J. C. +20 more
core +3 more sources
On the Connection Between Metal Absorbers and Quasar Nebulae [PDF]
, 2007 We establish a simple model for the distribution of cold gas around L* galaxies using a large set of observational constraints on the properties of strong MgII absorber systems.
Antonucci R. +17 more
core +2 more sources
Development and demonstration of end‐to‐end testing for intra‐fraction motion‐managed workflows
Medical Physics, Volume 52, Issue 9, September 2025.Abstract Background Intra‐fraction motion management techniques, including beam gating and intra‐fraction drift correction (IDC), have recently been introduced on the Unity MR‐linac (Elekta AB, Stockholm, Sweden) to mitigate the dosimetric impact of motion during treatment.
Stijn Oolbekkink +4 more
wiley +1 more source
Modeling quasar variability through self-organizing map-based neural process [PDF]
Serbian Astronomical JournalConditional Neural Process (QNPy) has shown to be a good tool for modeling quasar light curves. However, given the complex nature of the source and hence the data represented by light curves, processing could be time-consuming.
Čvorović-Hajdinjak I.
doaj +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
The Astrophysical JournalQuasars could serve as standard candles if the relation between their ultraviolet (UV) and X-ray luminosities can be accurately calibrated. Previously, we developed a model-independent method to calibrate quasar standard candles using the distance ...
Xiaolei Li +2 more
doaj +1 more source
, 2007 (Abridged) We develop a model for the cosmological role of mergers in the evolution of starbursts, quasars, and spheroidal galaxies. Combining halo mass functions (MFs) with empirical halo occupation models, we calculate where major galaxy-galaxy mergers
Athanassoula E. +21 more
core +1 more source
Cosmological Origin of Quasars [PDF]
Annals of the New York Academy of Sciences, 1995 Quasars are the earliest objects known to exist. We examine their origin in the context of popular models for structure formation in the universe. We show that seeds for quasar black holes could have originated from the initial cosmological collapse of overdense regions with unusually small rotation.
openaire +3 more sources
Discovery of Two Spectroscopically Peculiar, Low-Luminosity Quasars at z~4 [PDF]
, 2007 We report the discovery of two low-luminosity quasars at z~4, both of which show prominent N IV] 1486A emission. This line is extremely rare in quasar spectra at any redshift; detecting it in two out of a sample of 23 objects (i.e., ~ 9% of the sample ...
Ashish Mahabal +5 more
core +2 more sources