Results 51 to 60 of about 771 (176)
Radio Loud and Radio Quiet Quasars
, 2016 We discuss 6 GHz JVLA observations covering a volume-limited sample of 178 low redshift ($0.2 < z < 0.3$) optically selected QSOs. Our 176 radio detections fall into two clear categories: (1) About $20$\% are radio-loud QSOs (RLQs) having spectral luminosities $L_6 \gtrsim 10^{\,23.2} \mathrm{~W~Hz}^{-1}$ primarily generated in the active ...
Kellermann, K. I. +4 more
openaire +2 more sources
The Case for Two Quasar Populations
Open Astronomy, 2011 We present evidence for two populations of quasars showing distinctly different broad line structure and kinematics. The first evidence for quasar dichotomy involve differences between radio-quiet and radio-loud sources.
Sulentic Jack +2 more
doaj +1 more source
CLEAR EVIDENCE FOR INTRANIGHT OPTICAL VARIABILITY IN RADIO-QUIET QUASARS [PDF]
, 2020 We present new clues to the problem of the radio loudness dichotomy arising from an extensive search for intranight optical variability in seven sets of optically luminous radio-quiet quasars and (radio-loud) BL Lacertae objects, which are matched in ...
core
On the Selection of High-z Quasars Using LOFAR Observations
Frontiers in Astronomy and Space Sciences, 2018 We present a method to identify candidate quasars which combines optical/infrared color selection with radio detections from the Low Frequency ARray (LOFAR) at 150 MHz.
Edwin Retana-Montenegro +1 more
doaj +1 more source
Unveiling the origin of the radio emission in radio-quiet quasars [PDF]
Astronomy & Astrophysics, 2016 The origin of the radio emission in radio-quiet quasars (RQQs) has been a matter of debate for a long time. It is not well understood whether the emission is caused by star formation in the host galaxy or by black hole activity of the active galactic nuclei (AGN).
Herrera Ruiz, Noelia +3 more
openaire +3 more sources
The Astrophysical JournalWe investigate the group-scale environment of 15 luminous quasars (luminosity L _3000 > 10 ^46 erg s ^−1 ) from the Cosmic Ultraviolet Baryon Survey (CUBS) at redshift z ≈ 1.
Jennifer I-Hsiu Li +13 more
doaj +1 more source
A Comparative Study of VTEC Estimates Derived From S/X VLBI and VGOS Observations
Space Weather, Volume 23, Issue 12, December 2025.Abstract The ionosphere, which strongly varies in time and space, is one of the largest error sources for microwave measurements, if not accounted for accurately. Especially for single‐frequency observations, precise ionospheric models are needed to correct for the ionospheric delays. This study explores the utility of Very Long Baseline Interferometry
Arno Rüegg +2 more
wiley +1 more source
Radio-loudness Statistics of Quasars from Quaia-VLASS
The Astrophysical Journal Supplement SeriesQuasars are objects of high interest in extragalactic astrophysics, cosmology, and astrometry. One of their useful qualities is their potential radio-loudness.
Nestor Arsenov +3 more
doaj +1 more source
UEG Week 2023 Oral Presentations
, 2023 United European Gastroenterology Journal, Volume 11, Issue S8, Page 9-200, October 2023.
wiley +1 more source
Impact of Radio-mode Feedback on the Covering Fraction of the Circumgalactic Medium of Quasars
The Astrophysical JournalUtilizing data from the Low-Frequency Array Two-meter Sky Survey and the Sloan Digital Sky Survey, we assemble a sample of 1469 projected quasar pairs with detected radio emissions from foreground quasars, as well as a control sample of 5846 pairs ...
Wen-Qiang Liang +4 more
doaj +1 more source