Related papers: Discovery of Candidate X-ray Jets in High-Redshift…
We present Chandra X-ray (0.2-8 keV) and Very Large Array radio (15 and 5 GHz) images of the $\gamma$-ray bright, superluminal quasar 0827+243. The X-ray jet bends sharply--by ~90 deg., presumably amplified by projection effects--5'' from…
We report on the Swift/XRT observation and classification of eleven blazar candidates at $z>4$. These sources were selected as part of a sample of extremely radio-loud quasars, in order to focus on quasars with jets oriented roughly close…
Two relativistic X-ray jets have been detected with the Chandra X-ray observatory from the black hole X-ray transient XTE J1550-564. We report a full analysis of the evolution of the two jets with a gamma-ray burst external shock model. A…
We present multiwaveband observations of a well selected sample of 28 quasars and two radio galaxies with flat radio spectra and strong millimeter wave emission (referred to here as FSRQ's). The observations include multifrequency VLBI…
We report on observations of a TypeII quasar at redshift z=3.288, identified as a hard X-ray source in a 185 ks observation with the Chandra X-ray Observatory and as a high-redshift photometric candidate from deep, multiband optical…
We present three new Chandra X-ray epochs along with new ground-based optical-UV observations as the third installment in a time-series analysis of four high-redshift ($z\sim4.1-4.4$) radio-quiet quasars (RQQs). In total, we present nine…
We present the jet kinematics of the flat spectrum radio quasar (FSRQ) 4C +21.35 using time-resolved KaVA very long baseline interferometry array radio maps obtained from September 2014 to July 2016. During two out of three observing…
We match quasars discovered in a multi-color survey centered on the northern Hubble Deep Field (HDF) with radio sources from an ultra-deep radio survey. Although 3 out of 12 quasars are detected at a level below 0.2 mJy at 1.4 GHz, all of…
We present a study of the relation between X-rays and ultraviolet emission in quasars for a sample of broad-line, radio-quiet objects obtained from the cross-match of the Sloan Digital Sky Survey DR14 with the latest Chandra Source Catalog…
Despite the fact that kpc-scale inverse-Compton (iC) scattering of cosmic microwave background (CMB) photons into the X-ray band is mandated, proof of detection in resolved quasar jets is often insecure. High redshift provides favourable…
Obscuration in high-redshift quasi-stellar objects (QSO) has a profound impact on our understanding of the evolution of supermassive black holes across the cosmic time. An accurate quantification of its relevance is therefore mandatory. We…
We present results from deep (70 ks) Chandra ACIS observations and Hubble Space Telescope ACS F475W observations of two highly optically polarized quasars belonging to the MOJAVE blazar sample, viz., PKS B0106+013 and 1641+399 (3C345).…
We present Chandra observations of 2106 radio-quiet quasars in the redshift range 1.7<z<2.7 from the Sloan Digital Sky Survey (SDSS), through data release fourteen (DR14), that do not contain broad absorption lines (BAL) in their rest-frame…
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…
The X-ray spectrum of the Galactic microquasar SS 433 contains a rich set of emission lines of highly ionized atoms of heavy elements whose significant Doppler shift leaves no doubt that they are produced in collimated relativistic jets of…
We report the discovery of extended X-ray emission around the powerful high-redshift quasar GB 1508+5714 at z=4.3, revealed in a long Chandra ACIS observation. The emission feature is 3-4 arcsec away from the quasar core, which corresponds…
We present results of a study of 12 dust-reddened quasars with 0.4 < z < 2.65 and reddenings in the range 0.15 < E(B-V) < 1.7. We obtained ACIS-S X-ray spectra of these quasars, estimated the column densities towards them, and hence…
We present short \chandra observations of twelve bright (i<18) z_em~1.5 quasars from the Sloan Digital Sky Survey chosen to have significantly redder optical colors than most quasars at the same redshift. Of the five quasars with optical…
We investigate the radio emitting structures of radio-quiet active galactic nuclei with an emphasis on radio-quiet quasars to study their connection to Seyfert galaxies. We present and analyse high-sensitivity VLA radio continuum images of…
We report the Chandra detection of resolved X-ray emission of luminosity 3.5 \times 10^{40} ergs s^{-1} (0.4--4.5 keV) and power-law energy spectral index alpha = 1.5 \pm 0.7 from a roughly 10 arcsec length of the north-west radio jet in…