相关论文: Significant Limb-Brightening in the Inner Parsec o…

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…

We report on new developments in VLBI, with emphasis on experiments performed at the highest frequencies possible to date (so called mm-VLBI). We have observed the nucleus of M 87 (Virgo A) with global VLBI at 3 mm. We show a new image of…

Very long baseline interferometry observations reveal that relativistic jets like the one in M87 have a limb-brightened, double-edged structure. Analytic and numerical models struggle to reproduce this limb-brightening. We propose a model…

Analysis of comprehensive monitoring of 34 gamma-ray bright quasars, BL Lac objects, and radio galaxies reveals a close connection between events in the millimeter-wave emission imaged with the VLBA at 43 GHz and flares at gamma-ray and…

Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of BL Lac objects class, complicate the scenario in this already puzzling class of objects. Understanding the jet geometry, in connection…

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…

The $\gamma$-ray bright blazar CTA 102 is studied using imaging (new 15 GHz and archival 43 GHz Very Long Baseline Array, VLBA data) and time variable optical flux density, polarization degree and electric vector position angle (EVPA)…

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…

We compare the \gamma-ray light curves of the blazars, constructed with data provided by the Fermi Large Area Telescope, with flux and polarization variations in the VLBI core and bright superluminal knots obtained via monthly monitoring…

We analysed the parsec-scale linear polarization properties of 436 active galactic nuclei (AGN) based on 15 GHz polarimetric Very Long Baseline Array (VLBA) observations. We present polarization and total intensity images averaged over at…

We present total intensity and linear polarization images of OJ287 at 1.68GHz, obtained through space-based VLBI observations with RadioAstron on April 16, 2016. The observations were conducted using a ground array consisting of the VLBA…

(abridged) Very long baseline interferometry (VLBI) observations at 86$\,$GHz (wavelength, $\lambda = 3\,$mm) reach a resolution of about 50 $\mu$as, probing the collimation and acceleration regions of relativistic outflows in active…

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…

We present and discuss new result from mm-VLBI observations of M87 and SgrA*, using the Global mm-VLBI array (GMVA). New 3mm-VLBI images of the inner jet of M87 are presented, showing details with a spatial resolution down to 15…

We use observations of six "blazars" with the Very Long Baseline Array (VLBA), at eight frequencies (4.6, 5.1, 7.9, 8.9, 12.9, 15.4, 22.2, 43.1 GHz), to investigate the frequency-dependent position of their VLBI cores ("core-shift") and…

We present new radio observations of 9 members of a sample of 29 nearby (z < 0.2) BL Lac objects. The new data have been obtained with the European VLBI Network and/or the MERLIN at 1.6 and 5 GHz and complement previous observations. For…

In this first of a series of papers describing polarimetric multifrequency Very Long Baseline Array (VLBA) monitoring of 3C 273 during a simultaneous campaign with the INTEGRAL gamma-ray satellite in 2003, we present 5 Stokes I images and…

We present the detection of a radio-emitting jet from the black-hole candidate and X-ray binary source Cygnus X-1. Evidence of a bright core with a slightly extended structure was found on milliarcsecond resolution observations with the…

3C84 (NGC1275) is one of the brightest radio sources in the mm radio-bands, which led to a plethora of VLBI observations at numerous frequencies over the years. They reveal a two-sided jet structure, with an expanding but not…

We report on multifrequency radio observations made with the Effelsberg 100-m telescope, the IRAM 30-m telescope and the Green Bank Interferometer between 1992 and 1994 of the $\gamma$-ray quasar 0528+134. We present a new VLBI based map of…