Results 31 to 40 of about 166 (155)

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., Condon, J. J., Kimball, A. E., Perley, R. A., Ivezic, Zeljko   +4 more
openaire   +2 more sources

Winds Versus Jets in Active Galactic Nuclei

Galaxies
The well-established anti-correlation between disk winds and relativistic jets in X-ray binaries is often interpreted in a scale-invariant black hole accretion context. If so, active galactic nuclei (AGN) should exhibit a direct mass-scaled analog.
David Garofalo, Chandra B. Singh, Atticus Magerko, Marco Botello, Sophia Soto, Max North   +5 more
doaj   +1 more source

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, Marziani Paola, Zamfir Sebastian   +2 more
doaj   +1 more source

The ultraviolet spectra of radio-loud and radio-quiet quasars [PDF]

The Astronomical Journal, 1993
The rest-frame ultraviolet spectral properties of matched samples of radio-loud, radio-moderate, and radio-quiet quasars are investigated, using quasars drawn from the Large Bright QSO Survey. We confirm the absence of spectral differences between radio-loud and radio-quiet quasars at rest-frame wavelengths longward of 1600 A, as reported by previous ...
Francis, Paul, Hooper, Eric J., Impey, Chris D.   +2 more
openaire   +2 more sources

The Cosmic Ultraviolet Baryon Survey (CUBS). VIII. Group Environment of the Most Luminous Quasars at z ≈ 1

The Astrophysical Journal
We 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, Sean D. Johnson, Erin Boettcher, Sebastiano Cantalupo, Hsiao-Wen Chen, Mandy C. Chen, David R. DePalma, Zhuoqi (Will) Liu, Nishant Mishra, Patrick Petitjean, Zhijie Qu, Gwen C. Rudie, Joop Schaye, Fakhri S. Zahedy   +13 more
doaj   +1 more source

Hidden No More: Spotlight on Tidal Disruption Events in Active Galactic Nuclei

Astronomische Nachrichten, Volume 347, Issue 5, June 2026.
ABSTRACT Tidal disruption events (TDEs) are typically discovered in previously quiescent galaxies. However, earlier studies have revealed a handful of TDEs occurring in pre‐existing active galactic nuclei (AGN). We discuss AT2019aalc, a promising TDE candidate in an AGN, and compare it to similar sources.
Patrik Milán Veres
wiley   +1 more source

Optical Microvariability in Radio-quiet Quasars

The Astronomical Journal, 2006
We report the results of a study of optical microvariability in radio-quiet and radio-intermediate quasars. Observations were obtained on a total of seven objects: five radio-quiet quasars and two radio-intermediate quasars. No microvariability was detected in either the radio-quiet or radio-intermediate objects in our sample, despite intensive ...
M. T. Carini, J. C. Noble, R. Taylor, R. Culler   +3 more
openaire   +1 more source

Radio-loudness Statistics of Quasars from Quaia-VLASS

The Astrophysical Journal Supplement Series
Quasars are objects of high interest in extragalactic astrophysics, cosmology, and astrometry. One of their useful qualities is their potential radio-loudness.
Nestor Arsenov, Sándor Frey, András Kovács, Lyuba Slavcheva-Mihova   +3 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, Grzegorz Kłopotek, Benedikt Soja   +2 more
wiley   +1 more source

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, Huub Röttgering   +1 more
doaj   +1 more source