Related papers: Boundary Shear Acceleration in the Jet of MKN501

We discuss a role of the boundary shear layer of large scale jets for their observed multiwavelength emission. We consider a simple mechanism of a turbulent particle acceleration acting within such regions as an alternative mechanism with…

It has become commonplace is astronomy to describe the transverse coarse structure of jets in loosely defined terms such as "sheath" and "spine" based on discussions of parsec scale properties. But, the applicability, dimension and…

It has been proposed that blazar jets are structured, with a fast spine surrounded by a slower sheath or layer. This structured jet model explains some properties of their emission and morphology. Because of their relative motion, the…

Recent radio and optical large scale jets' observations suggest a two-component jet morphology, consisting of a fast central spine surrounded with a boundary layer with a velocity shear. We study radiation of electrons accelerated at such…

We present three 43 GHz images and a single 86 GHz image of Markarian 501 from VLBA observations in 2005. The 86 GHz image shows a partially resolved core with a flux density of about 200 mJy and a size of about 300 Schwarzschild radii,…

We report the first observation of the nearby giant radio galaxy NGC 315 using a global VLBI array consisting of 22 radio antennas located across five continents, including high-sensitivity stations, at 22 GHz. Utilizing the extensive…

We present the results of a high angular resolution study of the BL Lac object Markarian 501 in the radio band. We consider data taken at 14 different epochs, ranging between 1.6 GHz and 22 GHz in frequency, and including new Space VLBI…

We consider radiation of relativistic electrons accelerated within the jet extended boundary layer. Due to velocity shear across the boundary the observed jet/counterjet brightness ratio is diminished as compared to the one derived for the…

We present here two epochs of Space VLBI Observations at 18 cm of the BL-Lac type object MKN 501. Thanks to the high resolution of these new data, we have found that the inner jet is centrally brightened at its beginning, but becomes…

We present here two epochs of Space VLBI observations at 18 cm of the BL-Lac type object Mkn 501. Thanks to the high resolution of these new data we have found that the inner jet is centrally brightened at its beginning but becomes extended…

A simple model of cosmic ray electron acceleration at the jet boundary (Ostrowski 2000) yields a power-law particle energy distribution of ultrarelativistic electrons with an energy cut-off growing with time and finally, a growing particle…

We present a high-frequency very long baseline interferometry (VLBI) kinematical study of the BL Lac object S5 0716+714 over the time period of September 2008 to October 2010. The aim of the study is to investigate the relation of the jet…

Parsec scale jet properties are shortly presented and discussed. Observational data are used to derive constraints on the jet velocity and orientation, the presence of velocity structures, and the connection between the pc and kpc scale.…

We discuss processes accelerating cosmic ray electrons at boundaries of relativistic jets. The resulting spectrum is expected to posses two characteristic components: a power-law distribution at lower energies and a harder high energy…

We consider the acceleration of energetic particles by a velocity shear in the relativistic background flow containing scattering centers. Three possible acceleration sites for astrophysical jets are identified: (1) gradual velocity shear…

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…

The jet axes and the orbital planes of microquasar systems are usually assumed to be approximately perpendicular, eventhough this is not currently an observational requirement. On the contrary, in one of the few systems where the relative…

The radiation physics of gamma-ray bursts (GRBs) remains an open question. Based on the simulation analysis and recent observations, it was proposed that GRB jets are composed of a narrow ultra-relativistic core surrounded by a wide…

We report new 2 cm VLBA images of the inner radio jet of M87 showing a limb brightened structure and unambiguous evidence for a faint 3 mas long counter-feature which also appears limb brightened. Multi-epoch observations of seven separate…

By general relativistic magnetohydrodynamic simulations, it is suggested that the rotational energy of a rapidly rotating black hole (BH) is preferentially extracted along the magnetic field lines threading the event horizon in the middle…