Results 41 to 50 of about 183 (149)

Cross‐Polarization Gain Calibration of Linearly Polarized VLBI Antennas by Observations of 4C 39.25

Radio Science, Volume 59, Issue 4, April 2024.
Abstract Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high‐precision geodesy and astrometry. In order to achieve the maximum signal‐to‐noise ratio, the visibilities of all four polarization products are ...
F. Jaron, I. Martí‐Vidal, M. Schartner, J. González‐García, E. Albentosa‐Ruiz, S. Bernhart, J. Böhm, J. Gruber, S. Modiri, A. Nothnagel, V. Pérez‐Díez, T. Savolainen, B. Soja, E. Varenius, M. H. Xu   +14 more
wiley   +1 more source

A Surprising Excess of Radio Emission in Extremely Stable Quasars: A Unique Clue to Jet Launching?

The Astrophysical Journal
Quasars are generally divided into jetted radio-loud and nonjetted radio-quiet ones, but why only 10% of quasars are radio-loud has been puzzling for decades.
Wen-Yong Kang, Jun-Xian Wang, Zhen-Yi Cai, Hao-Chen Wang, Wen-Ke Ren, Mai Liao, Feng Yuan, Andrzej Zdziarski, Xinwu Cao   +8 more
doaj   +1 more source

Intranight optical variability of BL Lacs, radio-quiet quasars and radio-loud quasars [PDF]

Monthly Notices of the Royal Astronomical Society, 2005
8 pages, 3 Postscript figures, Accepted for publication in MNRAS, uses mn2e ...
Stalin, C. S., Gupta, A. C., Gopal-Krishna, Wiita, P. J., Sagar, R.   +4 more
openaire   +2 more sources

Why Radio Quiet Quasars are Preferred over Radio Loud Quasars Regardless of Environment and Redshift [PDF]

The Astrophysical Journal, 2020
Abstract Evidence has accumulated suggesting the clustering of radio loud quasars (RLQs) is greater than for radio quiet quasars. We interpret these results in a context in which the fraction of RLQ formation is f RLQ ≤ f RQQ compared to that for radio quiet quasars for all environments and redshifts ...
David Garofalo, Max North, Leanne Belga, Kenzi Waddell   +3 more
openaire   +2 more sources

Broad absorption line variability in radio-loud quasars [PDF]

Monthly Notices of the Royal Astronomical Society, 2014
We investigate C IV broad absorption line (BAL) variability within a sample of 46 radio-loud quasars (RLQs), selected from SDSS/FIRST data to include both core-dominated (39) and lobe-dominated (7) objects. The sample consists primarily of high-ionization BAL quasars, and a substantial fraction have large BAL velocities or equivalent widths; their ...
Welling, C. A., Miller, B. P., Brandt, W. N., Capellupo, D. M., Gibson, R. R.   +4 more
openaire   +2 more sources

Varstrometry for Off-nucleus and Dual Sub-kiloparsec Active Galactic Nuclei (VODKA): Very Long Baseline Array Searches for Dual or Off-nucleus Quasars and Small-scale Jets

The Astrophysical Journal, 2023
Dual and off-nucleus active supermassive black holes are expected to be common in the hierarchical structure formation paradigm, but their identification at parsec scales remains a challenge due to strict angular resolution requirements.
Yu-Ching Chen, Xin Liu, Joseph Lazio, Peter Breiding, Sarah Burke-Spolaor, Hsiang-Chih Hwang, Yue Shen, Nadia L. Zakamska   +7 more
doaj   +1 more source

Powerful Radio-loud Quasars Are Triggered by Galaxy Mergers in the Cosmic Bright Ages

The Astrophysical Journal
While supermassive black holes are ubiquitous features of galactic nuclei, only a small minority are observed during episodes of luminous accretion. The physical mechanism(s) driving the onset of fueling and ignition in these active galactic nuclei (AGN)
Peter Breiding, Marco Chiaberge, Erini Lambrides, Eileen T. Meyer, S. P. Willner, Bryan Hilbert, Martin Haas, George Miley, Eric S. Perlman, Peter Barthel, Christopher P. O’Dea, Alessandro Capetti, Belinda Wilkes, Stefi A. Baum, Duccio F. Macchetto, William Sparks, Grant Tremblay, Colin Norman   +17 more
doaj   +1 more source

PG 1004+130: Hybrid Morphology Source or a Restarted FRII? A uGMRT Polarimetric Investigation

The Astrophysical Journal, 2023
We present the polarization image of the hybrid morphology and broad absorption line quasar PG 1004+130 at 694 MHz obtained with the upgraded Giant Metrewave Radio Telescope. We detect linear polarization in this source’s core, jets, and lobes.
Salmoli Ghosh, P. Kharb, J. Baghel, S. Silpa   +3 more
doaj   +1 more source

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

Near Infrared Micro-variability of Radio-loud Quasars [PDF]

Publications of the Astronomical Society of Australia, 2002
AbstractWe observed three AGN from the Parkes Half-Jansky Flat-spectrum Sample at near infrared (NIR) wavelengths to search for micro-variability. In one source, the blue quasar PKS 2243–123, good evidence for NIR micro-variability was found. In the other two sources, PKS 2240–260 and PKS 2233–148, both BL Lacertae objects, no such evidence of ...
Whiting, Matthew, Oshlack, Alicia, Webster, Rachel   +2 more
openaire   +2 more sources