Related papers: Large-Scale Radio and X-ray Jets in the Highest Re…

We present results from 1.4 and 5 GHz observations at matched resolution with the Karl G. Jansky Very Large Array (VLA) of 11 powerful 3C FR II quasars. We examine the 11 quasars along with a sample of 13 narrow-line FR II radio galaxies…

We report detections of six high-redshift (1.8 < z < 6.4), optically luminous, radio-quiet quasars at 350 micron, using the SHARC II bolometer camera at the Caltech Submillimeter Observatory. Our observations double the number of…

The prominent radio quasar PKS 2215+020 (J2217+0220) was once labelled as a new laboratory for core--jet physics at redshift z=3.572 because of its exceptionally extended jet structure traceable with very long baseline interferometric…

We examine the distribution of radio emission from ~42,000 quasars from the Sloan Digital Sky Survey, as measured in the LOFAR Two-Metre Sky Survey (LoTSS). We present a model of the radio luminosity distribution of the quasars that assumes…

We observed 17 optically-selected, radio-quiet high-redshift quasars with the Chandra Observatory ACIS, and detected 16 of them. The quasars have redshift between 3.70 and 6.28 and include the highest redshift quasars known. When compared…

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…

Since its launch in 1999, the Chandra X-ray observatory has discovered several dozen X-ray jets associated with powerful quasars. In many cases the X-ray spectrum is hard and appears to come from a second spectral component. The most…

As part of our program to build a complete radio and X-ray database of all the 3CR extragalactic radio sources, we present an analysis of 93 sources for which Chandra archival data are available. Most of these sources have been already…

We have compiled a sample of 234 ultra-steep-spectrum (USS) selected radio sources in order to find high-redshift radio galaxies. The sample covers the declination range -40deg < DEC < -30deg in the overlap region between the 1400-MHz NRAO…

Since mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope. One of the main goals of this programme is to study the relation between the radio and…

We discuss radio observations of a sample of radio-weak and radio-intermediate quasars which demonstrate that - just like their radio-loud counterparts - radio-weak quasars too have relativistic jets in their nuclei. Moreover, a VLA survey…

We present Ly$\alpha$, He II and C IV observations of 7 redshift ~ 2 radio-loud quasars observed using the Keck Cosmic Web Imager (KCWI) and compare it to observed radio jet emission using archival VLA and ALMA radio observations. We detect…

We present preliminary results from HST imaging of radio-loud quasar hosts, covering a ~x100 range in radio luminosity but in a narrow redshift range (0.5 to 0.65). The sample was selected from our new, spectroscopically complete 7C survey…

The radiative and jet power in active galactic nuclei is generated by accretion of material on to supermassive galactic-centre black holes. For quasars, where the radiative power is by definition very high, objects with high radio…

We present polarization images with the Karl G. Jansky Very Large Array (VLA) in A and B-array configurations at 6 GHz of 7 radio-loud (RL) quasars and 8 BL Lac objects belonging to the Palomar-Green (PG) `blazar' sample. This completes our…

Radio-loud quasars at high redshift (z > 4) are rare objects in the Universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density sufficiently high for monitoring of their apparent position.…

Blazars are a sub-class of quasars with Doppler boosted jets oriented close to the line of sight, and thus efficient probes of supermassive black hole growth and their environment, especially at high redshifts. Here we report on Very Long…

This paper presents multiwavelength imaging and broad-band spectroscopy of the relativistic jets in the two nearby radio galaxies 3C 371 and PKS 2201+044, acquired with Chandra, HST, VLA, and Merlin. Radio polarization images are also…

We are conducting a multi-wavelength (radio, optical, and X-ray) observational campaign to classify, morphologically and physically, a sample of 55 flat-spectrum radio sources dominated by structure on kpc-scales. This sample contains 22…

We report on a search for X-ray emission from quasars with redshifts greater than four using the ROSAT public database. Our search has doubled the number of z>4 quasars detected in X-rays from 6 to 12. Most of those known prior to this work…