Related papers: Radio-loud fraction of z>6 quasars

We present Very Large Array observations at 1.4 and 5 GHz of a sample of 16 quasi-stellar objects (QSOs) at z = 1.78 to 2.71. Half of the chosen quasars are bright at mm wavelengths (250 or 350 GHz) while the other half were not detected at…

We present the low-frequency radio spectra of 9 high-redshift quasars at $5.6 \leq z \leq 6.6$ using the Giant Metre Radio Telescope band-3, -4, and -5 observations ($\sim$300-1200 MHz), archival Low Frequency Array (LOFAR; 144 MHz), and…

Although radio-quiet quasars (RQQs) constitute >90% of optically-identified quasar samples their radio properties are only poorly understood. In this paper we present the results of a multi-frequency VLA study of 27 low-redshift RQQs. We…

We present results of a new, large survey for high-redshift radio-loud quasars, which targets quasars with z>4. The survey is based on the PMN and NVSS radio surveys, optically identified using digitised UKST B, R and I plates. Six new z>4…

We have performed a search over 3440 deg$^2$ of Epoch 1 (2017-2019) of the Very Large Array Sky Survey to identify unobscured quasars in the optical ($0.2 < z < 3.2$) and obscured active galactic nuclei (AGN) in the infrared that have…

We present new millimeter and radio observations of nine z~6 quasars discovered in deep optical and near-infrared surveys. We observed the 250 GHz continuum in eight of the nine objects and detected three of them. New 1.4 GHz radio…

We report on European VLBI Network (EVN) and Very Large Array (VLA) observations of SDSS J0836+0054, the most distant radio-loud quasar known at present z=5.774). The source, with a total flux density of 1.1 mJy, shows a compact structure…

We present 6-GHz Very Large Array radio images of 70 gravitational lens systems at 300-mas resolution, in which the source is an optically-selected quasar, and nearly all of which have two lensed images. We find that about in half of the…

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…

Luminous quasars at $z>4$ provide key insights into the early Universe. Their rarity necessitates wide-field multi-band surveys to efficiently separate them from the main astrophysical contaminants (i.e., ultracool dwarfs). To expand the…

There are approximately 250 quasars discovered at redshift $z\geq6$, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we…

We present the discovery of the radio-loud quasar PSO J352.4034-15.3373 at z=5.84 pm 0.02. This quasar is the radio brightest source known, by an order of magnitude, at z~6 with a flux density in the range of 8-100 mJy from 3GHz to 230MHz…

We have made radio observations of 87 optically selected quasars at 5 GHz with the VLA in order to measure the radio power for these objects and hence determine how the fraction of radio-loud quasars varies with redshift and optical…

The interactions between radio jets and the interstellar medium play a defining role for the co-evolution of central supermassive black holes and their host galaxies, but observational constraints on these feedback processes are still very…

We have carried out multicolour imaging of a complete sample of radio-loud quasars at 0.6 < z < 1.1 and find groups or clusters of galaxies in the fields of at least 8 and possibly 13 of the 21 sources. There is no evidence for an evolution…

High-redshift quasars are currently the only probes of the growth of supermassive black holes and potential tracers of structure evolution at early cosmic time. Here we present our candidate selection criteria from the Panoramic Survey…

We have obtained complete redshift information for a sample of 442 radio-loud quasars with flux densities S(11cm) >= 0.25Jy. These come from a completely-identified sample of 878 flat-spectrum radio sources, so there is no optical magnitude…

Radio sources at the highest redshifts can provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. The number of astronomical objects identified at z>6…

We report on the search for distant radio-loud quasars in the Cosmic Lens All Sky Survey (CLASS) of flat spectrum radio sources with S_5GHz>30 mJy. Unresolved optical counterparts were selected from APM scans of POSS-I plates, with e<19.0…

We define a new complete sample of 13 optically-luminous radio quasars M_AB(1450 Angstrom) < -26.9 mag and log P_1.4 GHz(W/Hz) > 25.7 with redshift 3.8 < z < 4.5, obtained by cross-correlating the FIRST radio survey and the APM catalogue of…