Results 41 to 50 of about 719 (181)
Phylogenetic Analyses of Quasars and Galaxies
Frontiers in Astronomy and Space Sciences, 2017 Phylogenetic approaches have proven to be useful in astrophysics. We have recently published a Maximum Parsimony (or cladistics) analysis on two samples of 215 and 85 low-z quasars (z < 0.7) which offer a satisfactory coverage of the Eigenvector 1 ...
Didier Fraix-Burnet +2 more
doaj +1 more source
The Astrophysical Journal, 2023 We constrain the emission mechanisms responsible for the prodigious electromagnetic output generated by active galactic nuclei (AGNs) and their host galaxies with a novel state-of-the-art AGN radio-to-X-ray spectral energy distribution model fitting code
Mojegan Azadi +14 more
doaj +1 more source
Unveiling Radio Loudness in Quasars
, 2003 We present a new approach to tackle the issue of radio loudness in quasars. We constrain a (simple) prescription for the intrinsic distribution of radio-to-optical ratios by comparing properties of Monte Carlo simulated samples with those of observed optically selected quasars.
Cirasuolo, M. +3 more
openaire +2 more sources
Blueshifted Fe ii and Balmer Broad Emission lines in a Reddened Quasar
The Astrophysical Journal, 2023 We present detailed analysis of the optical and near-infrared spectrum of the reddened radio-loud quasar F2M J154043.74+492323.9 with strong optical Fe ii emission of ${R}_{4570}\equiv \tfrac{\mathrm{Fe}\,{\rm\small{II}}\lambda \lambda \,4434,4684}{{\rm ...
Yipeng Zhou +3 more
doaj +1 more source
Resolving the Powerful Radio-loud Quasar at z ∼ 6 [PDF]
The Astrophysical Journal, 2018 We present high angular resolution imaging ($23.9 \times 11.3$ mas, $138.6 \times 65.5$ pc) of the radio-loud quasar PSO~J352.4034$-$15.3373 at $z=5.84$ with the Very Long Baseline Array (VLBA) at 1.54 GHz. This quasar has the highest radio-to-optical flux density ratio at such a redshift, making it the radio-loudest source known to date at $z \sim 6$.
Emmanuel Momjian +4 more
openalex +5 more sources
Hidden Blazars In Radio Loud Quasars? [PDF]
Symposium - International Astronomical Union, 2000 We present the initial results from our search for hidden blazars via CIV emission line variability among radio loud quasars. The implications on models of quasar Broad Emission Line Regions are discussed, and we focus on the tidally disrupted star model.
openaire +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 +2 more
openaire +2 more sources
The Astrophysical JournalThe 21 cm forest is a sensitive probe for the early heating process and small-scale structures during the epoch of reionization (EOR), to be realized with the upcoming Square Kilometre Array (SKA). Its detection relies on the availability of radio-bright
Qi Niu +4 more
doaj +1 more source
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 +14 more
wiley +1 more source
A Surprising Excess of Radio Emission in Extremely Stable Quasars: A Unique Clue to Jet Launching?
The Astrophysical JournalQuasars 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 +8 more
doaj +1 more source