Related papers: The jet collimation profile at high resolution in …

Recent VLBI studies of the morphology and kinematics of individual BL Lac objects (S5 1803+784, PKS 0735+178, etc.) have revealed a new paradigm for the pc-scale jet kinematics of these sources. Unlike the apparent superluminal outward…

We propose a unified classification for BL Lac objects (BLs), focusing on the synchrotron peak frequency of the spectral energy distribution. The unification scheme is based on the angle Theta that describes the orientation of the…

In recent years, the jet formation region in active galaxies has been imaged through mm-VLBI in few ideal targets, first and foremost M87. An important leap forward for understanding jet launching could be made by identifying a larger…

The existence of accreting supermassive black holes up to billions of solar masses at early cosmological epochs (in the context of this work, redshifts z>=6) requires very fast growth rates which is challenging to explain. The presence of a…

M87 provides the best opportunity to study the base of a jet where it is collimated and accelerated. The size of that region scales with the mass of the black hole, and M87 has the best combination of high mass, proximity to the Earth, and…

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…

With its high black hole mass, proximity, and bright jet, M87 provides the best prospect for a direct imaging study of the acceleration and collimation region of a jet. Previous VLBI observations have shown an edge brightened structure with…

We study the jet physics of the BL Lac object PKS 2233-148 making use of synergy of observational data sets in the radio and gamma-ray energy domains. The four-epoch multi-frequency (4-43 GHz) VLBA observations focused on the parsec-scale…

Supermassive black holes at the centre of active galactic nuclei power some of the most luminous objects in the Universe. Typically, very long baseline interferometric (VLBI) observations of blazars have revealed only funnel-like…

High resolution Very Long Baseline Interferometry (VLBI) observations of Active Galactic Nuclei (AGN) revealed traveling and stationary or quasi-stationary radio-components in several blazar jets. The traveling ones are in general…

We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample of $\gamma$-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 GHz under the VLBA-BU-BLAZAR program. We implement a…

We report radio imaging and monitoring observations in the frequency range 0.235 - 2.7 GHz during the flaring mode of PKS 2155-304, one of the brightest BL Lac objects. The high sensitivity GMRT observations not only reveal extended…

Using time-resolved multifrequency Very Long Baseline Array data and new KaVA (KVN and VERA Array) observations, we study the structure and kinematics of the jet of the flat spectrum radio quasar (FSRQ) 1928+738. We find two distinct jet…

Ground-space interferometer RadioAstron provides unique opportunity to probe detail structure of the distant active galactic nuclei at $\mu$as scales. Here we report on RadioAstron observations of the BL Lac object S5 0716$+$71, performed…

We present the results of a study on the 1.4 GHz kpc-scale radio emission in the complete flux density limited MOJAVE sample, comprising 135 radio-loud AGNs. While extended emission is detected in the majority of the sources, about 7% of…

We report on the acceleration properties of 329 features in 95 blazar jets from the MOJAVE VLBA program. Nearly half the features and three-quarters of the jets show significant changes in speed and/or direction. In general, apparent speed…

One of the most well-known extragalactic sources in the sky, quasar 3C 454.3, shows a curved parsec-scale jet that has been exhaustively monitored with very-long-baseline interferometry (VLBI) over the recent years. In this work, we present…

For the BL Lac object S5 0716+714 conflicting apparent velocities of jet component motion have been reported in the literature. This object is an intra-day variable source and suited to investigate a possible correlation between kinematic…

The origin of jet launching mainly comes from two mechanisms: the BZ mechanism and the BP mechanism. However, it is in debate which one is dominating in blazars. In this work, we used a sample of 937 Fermi blazars to study the jet formation…

Allowing for the conical shape of ultrarelativistic blazar jets with opening angles of a few degrees on parsec-scales we show that their bulk Lorentz factors and viewing angles can be much larger than the values usually inferred by…