Results 81 to 90 of about 24,041 (212)
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
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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.
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Journal of Applied Clinical Medical Physics, Volume 26, Issue 6, June 2025.Abstract Purpose This study aims to evaluate the accuracy of the frameless linear accelerator‐based stereotactic radiosurgery (FSRS) system incorporating cone‐beam CT (CBCT), six degrees of freedom (6‐DoF) couch, room laser, and surface image‐guided (SG) systems.
Hao‐Wen Cheng +4 more
wiley +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
Mimicking Symmetry‐Breaking Einstein Ring by Optical Lens
Advanced Photonics Research, Volume 6, Issue 6, June 2025.This article uses an optical lens to emulate the gravitational lensing effect and observe the Einstein ring (ER) patterns. The symmetry‐breaking ER, i.e., Einstein cross, is observed utilizing a rotation‐symmetry‐breaking hemi‐ellipsoid lens. Deformed Einstein cross patterns induced by noncollinearly alignment of the light source–lens–observer are ...
Jun‐Liang Duan +5 more
wiley +1 more source
The Astrophysical JournalQuasar-driven galactic outflows are a major driver of the evolution of massive galaxies. We report observations of a powerful galactic-scale outflow in a z = 3 extremely red and intrinsically luminous ( L _bol ≃ 5 × 10 ^47 erg s ^−1 ) quasar SDSSJ1652 ...
Andrey Vayner +27 more
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Astronomische Nachrichten, Volume 346, Issue 5, June 2025.ABSTRACT Classification of galaxies, stars, and quasars using spectral data is fundamental to astronomy, but often relies heavily on redshift. This study evaluates the performance of 10 machine learning algorithms on SDSS data to classify these objects, with a particular focus on scenarios where redshift information is unavailable.
Debashis Chatterjee, Prithwish Ghosh
wiley +1 more source
Medical Physics, Volume 52, Issue 6, Page 4598-4604, June 2025.Abstract Background Magnetic resonance imaging (MRI) offers superior soft tissue contrast and essential imaging capabilities for modern medicine. MRI is increasingly being used in applications that require a high degree of spatial fidelity; however, distortions are a well‐known limitation of the modality. The mid‐field (0.3 T ≤ B0 < 1 T) has advantages
Curtis N. Wiens +2 more
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, 2002 Review on quasar lensing. Part of a LNP Topical Volume "Dark matter and gravitational lensing" (eds. Courbin, Minniti) to be published by Springer-Verlag, 2002. Paper with full resolution figures at: ftp://ftp.astro.ulg.ac.be/pub/users/courbin/
Courbin, F., Saha, P., Schechter, P. L.
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Surveying the Onset and Evolution of Supermassive Black Holes at High-z with AXIS
UniverseThe nature and origin of supermassive black holes (SMBHs) remain an open matter of debate within the scientific community. While various theoretical scenarios have been proposed, each with specific observational signatures, the lack of sufficiently ...
Nico Cappelluti +9 more
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