Related papers: A new method for estimating frequency-dependent co…
The quasar 3C345 is one of the best examples of extragalactic jet with superluminal components moving on helical paths. To get better constraints on the jet physics, we have imaged the source at the highest possible resolution, using…
We made VLBI observations at 8.4 GHz between 1997 and 2005 to estimate the coordinates of the "core" component of the superluminal quasar, 3C 454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope…
The results of VLBI observations of the quasar 3C273, obtained during a multi-frequency campaign in late 1992 in the radio, millimeter and X-ray bands are presented and discussed. The VLBI observations were made at 22 GHz with a Global…
The 16th magnitude quasar 3C 345 (redshift z=0.5928) shows structural and emission variability on parsec scales around a compact unresolved radio core. For the last three decades it has been closely monitored with very long baseline…
Ever since the discovery by the Fermi mission that active galactic nuclei (AGN) produce copious amounts of high-energy emission, its origin has remained elusive. Using high-frequency radio interferometry (VLBI) polarization imaging, we…
We present the multi-frequency, multi-epoch Very Long Baseline Interferometry (VLBI) study of the two-sided jets in the low-luminosity active galactic nucleus NGC 3998, where physical properties of the jets on parsec scales remain poorly…
The advent of global mm-band Very Long Baseline Interferometry (VLBI) in recent years has finally revealed the morphology of the base of the two most prominent nearby, bright, extragalactic radio jets in M\,87 and 3C\,84. The images are…
We present the first 86 GHz VLBI observations of the radio galaxy 3C~120, together with contemporaneous 43 and 22 GHz polarimetric VLBA observations. The very high angular resolution obtained at 86 GHz provides an upper limit to the size of…
Over the past few decades, our knowledge of jets produced by active galactic nuclei (AGN) has greatly progressed thanks to the development of very-long-baseline interferometry (VLBI). Nevertheless, the crucial mechanisms involved in the…
Previous spectral energy distribution modeling based on XMM-Newton X-ray observation of the classical double-lobed radio galaxy 3C 411 left the possibility open for the presence of a blazar-like core. We investigated this scenario by…
High resolution studies of circular polarization allow us see where it arises in a jet, study its local fractional level and spectrum, and compare these results to local measures of linear polarization and Faraday rotation. Here we not only…
Multi-epoch Very Long Baseline Interferometry (VLBI) study of the sub-pc scale jet of 3C 84 is presented. We carried out 14-epoch VLBI observations during 2006-2009 with the Japanese VLBI Network (JVN) and the VLBI Exploration of Radio…
We present the results of six-epoch Very Long Baseline Array (VLBA) observations of 3C~66A. The high-resolution Very Long Baseline Interferometer (VLBI) maps obtained at multi-frequency (2.3, 8.4, and 22.2 GHz) simultaneously enabled us to…
Nearby radio galaxies that contain jets are extensively studied with VLBI, addressing jet launching and the physical mechanisms at play around massive black holes. 3C 84 is unique in this regard, because the combination of its proximity and…
The Blandford and K\"{o}nigl model of AGN jets predicts that the position of the apparent opaque jet base - the core - changes with frequency. This effect is observed with radio interferometry and is widely used to infer parameters and…
Multi-epoch GHz Very Long Baseline Interferometry (VLBI) data of the radio-loud quasar J1101+7225 were analyzed to estimate the proper motion of extended optically thin jet components. Two components separated from the core could be mapped…
We report multi-epoch Very Long Baseline Interferometry (VLBI) study of the innermost jet of 3C 84. We carried out 14-epoch VLBI observations during 2006-2009 with the Japanese VLBI Network (JVN) and the VLBI Exploration of Radio Astrometry…
Radio galaxies harbouring jetted active galactic nuclei are a frequent target of very-long-baseline interferometry (VLBI) because they play an essential role in exploring how jets form and propagate. Hence, only few have not been detected…
Flares in radio-loud AGN are thought to be associated with the injection of fresh plasma into the compact jet base. Such flares are usually strongest and appear earlier at shorter radio wavelengths. Hence, VLBI at mm-wavelengths is best…
A bright optical flare was detected in the high-redshift ($z=2.133$) quasar CGRaBS J0809+5341 on 2014 April 13. The absolute magnitude of the object reached $-30.0$ during the flare, making it the brightest one (in flaring stage) among all…