Related papers: Varstrometry for Off-nucleus and Dual Sub-kpc AGN …

We present the results of a new spectroscopic survey for dusty intervening absorption systems, particularly damped Ly$\alpha$ absorbers (DLAs), towards reddened quasars. The candidate quasars are selected from mid-infrared photometry from…

We report the results of $g-$, $r-$, and $i-$dropout selections based on optical identifications of Very Large Array Sky Survey (VLASS) radio sources using the Hyper Suprime-Cam Subaru Strategic Program survey (HSC--SSP). By positional…

Blazars are active galactic nuclei (AGN) whose relativistic jets point nearly to the line of sight. Their compact radio structure can be imaged with very long baseline interferometry (VLBI) on parsec scales. Blazars at extremely high…

[ABRIDGED] We have carried out a systematic search for close supermassive black hole binaries among z < 0.7 SDSS quasars Such binaries are predicted by models of supermassive black hole and host galaxy co-evolution, therefore their census…

There is still a limited number of high-redshift ($z>3$) active galactic nuclei (AGN) whose jet kinematics have been studied with very long baseline interferometry (VLBI). Without a dedicated proper motion survey, regularly conducted…

We present a multi-wavelength investigation of radio sources in the globular cluster M22 (NGC6656) using VLA, HST, and Chandra observations. Among the eight identified counterparts, we highlight VLA22 as the most promising stellar-mass…

Active Galactic Nuclei (AGNs) observed with the technique of very long baseline interferometry (VLBI) are used as fiducial references on the sky to precisely measure the shape and orientation of the Earth. Their positions form a celestial…

The statistical study of the parsec scale properties of radio sources is crucial to get information on the nature of the central engine and to provide the foundations of the current unified theories, suggesting that the appearance of active…

High-resolution millimeter wave very-long-baseline interferometry (mm-VLBI) is an ideal tool for probing the structure at the base of extragalactic jets in detail. The TeV blazar Mrk 501 is one of the best targets among BL Lac objects for…

The high radio frequency polarization imaging of non-thermal emission from active galactic nuclei (AGN) is a direct way to probe the magnetic field strength and structure in the immediate vicinity of supermassive black holes (SMBHs) and is…

The Andromeda galaxy (M\,31) hosts one of the nearest and most quiescent super-massive black holes, which provides a rare, but promising opportunity for studying the physics of black hole accretion at the lowest state. We have conducted a…

As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0 GHz to obtain phase-referenced images of 76 sources in the NOAO Bootes field. These 76…

The Korean very-long-baseline interferometry (VLBI) network (KVN) and VLBI Exploration of Radio Astrometry (VERA) Array (KaVA) is the first international VLBI array dedicated to high-frequency (23 and 43 GHz bands) observations in East…

Quasars are very important in materializing the reference frame. The excess emission of AGNs (active galactic nuclei) in the mid infrared band can be used to identify quasar candidates. As extremely distant and point like objects, quasars…

We performed an automated comparison of the FIRST radio survey with the APM optical catalog to find radio lobes with optical counterparts. Based on an initial survey covering ~3000 square degrees, we selected a sample of 33 lens candidates…

We present a new sample of 30 nearby (z<0.2) BL Lacs, selected to study the nuclear as well as the large scale properties of low power radio sources. In this first paper, we show and discuss new radio data taken with the VLA (19 objects at…

We present analysis of Chandra X-ray observations of seven quasars that were identified as candidate sub-parsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey (CRTS) based on apparent periodicity in…

The orientation of the disk of material accreting onto supermassive black holes that power quasars is one of most important quantities that are needed to understand quasars -- both individually and in the ensemble average. We present a…

We observed with the VLBA at 2.3 and 8.6 GHz a complete flux-density limited sample of 482 radio sources with declination >+75 degrees brighter than 200 mJy at 1.4 GHz drawn from the NVSS catalog. 34% of the sources show parsec-scale…

We report milliarcsecond-scale VLBI detections of compact radio nuclei in four spiral-hosted, double-lobed radio-loud AGNs (spiral DRAGNs), a rare class that challenges the traditional association of powerful jets with elliptical hosts.…