Related papers: Dissecting the AGN disk-jet system with joint VLBI…
An increasing number of observations and simulations suggests that low-power (<10$^{44}$ erg s$^{-1}$) jets may be a significant channel of feedback produced by active galactic nuclei (AGN), but little is known about their actual effect on…
(abridged) Relativistic jets, formed in the vicinity of central supermassive black holes in AGN, show ample evidence connecting them to physical conditions in the accretion disc and broad-line region. The jets are responsible for a large…
We present our latest results on the connection between accretion rate and relativistic jet power in AGN, by using a large sample which includes mostly blazars, but contains also some radio--galaxies. The jet power can be traced by…
We extend previous works by considering two additional radio frequencies (K band and X/Ka band) with the aim to study the frequency dependence of the source positions and its potential connection with the physical properties of the…
We present the results of studying the accretion disk vs jet power for a large fraction of all the blazars detected by the Fermi Gamma-Ray Space Telescope. The disk power is inferred from the emission line luminosities obtained from…
We performed a comprehensive analysis of flux and color variability in a redshift-matched sample of Seyfert galaxies, comprising 23 gamma-ray-detected narrow-line Seyfert 1 galaxies (gNLS1s), 190 non-gamma-ray-detected narrow-line Seyfert 1…
Using photometric variability information from the new Gaia DR3 release, I show for the first time that photometric variability is inversely correlated with the prevalence of optical-radio position offsets in the active galactic nuclei…
Off-nucleus active galactic nuclei (AGN) can be signposts of inspiraling supermassive black holes (SMBHs) on galactic scales, or accreting SMBHs recoiling after the coalescence of a SMBH binary or slingshot from three-body interactions.…
The connection between the accretion process that powers AGN and the formation of jets is still poorly understood. Here we tackle this issue using new, deep \chandra and \xmm observations of the cores of three powerful radio loud quasars:…
Broadband spectrum of AGN consists of multiple components such as jet emission and accretion disk emission. Temporal correlation study is useful to understand emission components and their physical origins. We have performed optical…
Up to now, jet kinematic studies of radio quasars have barely reached beyond the redshift range at $z>3.5$. This significantly limits our knowledge of high-redshift jets, which can provide key information for understanding the jet nature…
Double-peaked emission lines in the narrow- and/or broad-line spectra of AGN have been suggested to arise due to disky broad/narrow line regions, jet-medium interaction, or the presence of binary supermassive black holes. We present the…
Observations made with the VLBA have led to fundamental advances in our understanding of how radio jets in AGN evolve from parsec-scales out to distances exceeding several hundred kiloparsecs. In this review I discuss current models of…
The long-term variability study over a range of black hole (BH) mass systems from the microquasars of stellar-mass black holes to the Active Galactic Nuclei (AGNs) of supermassive black holes, in $\gamma$-rays offers new insights into the…
Using millimeter-very long baseline interferometry (VLBI) observations of the BL Lac object S5 0716+714 from August 2008 to September 2013, we investigate variations in the core flux density and orientation of the sub-parsec scale jet i.e.…
The mechanism and the region of generation of variable continuum emission are poorly understood for radio-loud AGN because of a complexity of the nuclear region. High-resolution radio VLBI (very long baseline interferometry) observations…
While 2% of active galactic nuclei (AGNs) exhibit narrow emission lines with line-of-sight velocities that are significantly offset from the velocity of the host galaxy's stars, the nature of these velocity offsets is unknown. We…
Only in the radio-loud population of active galactic nuclei (AGN) does the production, collimation, and acceleration of powerful relativistic jets take place. We introduce here a concept of combined VLBI- and X-ray spectroscopic…
We present the results of a number of high resolution radio observations of the AGN 1156+295. These include multi-epoch and multi-frequency VLBI, VSOP, MERLIN and VLA observations made over a period of 50 months. The 5 GHz MERLIN images…
The latest results of the most detailed analysis of multi-epoch polarization-sensitive observations of active galactic nuclei (AGN) jets at parsecs scales by very long baseline interferometry (VLBI) reveal several characteristic patterns of…