ABSTRACT Observational studies of collimation in jets active galactic nuclei (AGN) are a key to understanding their formation and acceleration processes. We have performed an automated search for jet shape transitions sample 367 AGN using VLBA data at 15 1.4 GHz. This has found 10 out 29 nearby redshifts z < 0.07 with transition from parabolic conical shape, while the full analysed is dominated by distant typical ≈ 1. The ten UGC 00773, NGC 1052, 3C 111, 120, TXS 0815−094, Mrk 180,...

Introduction List of notation Constants and quantities 1. Basic observational characteristics radio pulsars 2. Neutron stars 3. Physical processes in the pulsar magnetosphere 4. Electrodynamics 5. Generation electron-positron plasma 6. Pulsar emission 7. Comparison theory with data Conclusion Appendix References Additional literature Author index Subject index.

The stationary axisymmetric outflow from a rotating sphere with (split) monopole magnetic field is considered. stream equation describing the linearized in terms of Michel magnetization parameter σ−1 ≪ 1, which allows self-consistent analysis direct problem. It shown that for finite σ fast magnetosonic surface located at distance ∼ σ1/3RL (RL = c/ΩF light cylinder). We have also found particle energy just equal to value γ σ1/3. acceleration and collimation are become ineffective outside surface.

The problem of the efficiency particle acceleration for a paraboloidal poloidal magnetic field is considered within approach steady axisymmetric magnetohydrodynamic (MHD) flow. For large Michel magnetization parameter σ it possible to linearize stream equation near force-free solution and solve self-consistently as was done by Beskin, Kuznetsova & Rafikov monopole field. It shown that, on fast magnetosonic surface (FMS), Lorentz factor γ does not exceed standard value σ1/3. On other hand, in...

In this review, analytical results obtained for a wide class of stationary axisymmetric flows in the vicinity compact astrophysical objects are analyzed, with an emphasis on quantitative predictions specific sources. Recent years have witnessed great increase understanding formation and properties jets. This is due not only to new observations but also advances theory which has produced fairly simple relations, what can undoubtedly be called breakthrough numerical simulation enabled...

We study the influence of propagation effects on mean profiles radio pulsars using method wave in inhomogeneous media described by Kravtsov & Orlov. This approach allows us first to take into consideration transition from geometrical optics vacuum propagation, cyclotron absorption and refraction simultaneously. In addition, non-dipole magnetic field configuration, drift motion plasma particles their realistic energy distribution are taken account. It is confirmed that, for ordinary (period P...

Abstract We propose a new method of estimating the mass supermassive black hole residing in centre an active galaxy. The galaxy M87 offers convenient test case for due to existence large amount observational data on jet and ambient environment properties central area object. suggest that observed transition boundary shape from parabolic conical form is associated with flow transiting magnetically dominated regime energy equipartition between plasma bulk motion magnetic field. By coupling...

The analysis of the frequency dependence observed shift cores relativistic jets in active galactic nuclei (AGN) allows us to evaluate number density outflowing plasma n e and, hence, multiplicity parameter λ = /n GJ , where is Goldreich-Julian density.We have obtained median value for med 3 • 10 13 and Michel magnetization σ M,med 8 from an 97 sources.Since can be interpreted as maximum possible Lorentz factor Γ bulk motion which magnetohydrodynamic (MHD) flow, this estimate agreement with...

Recent progress in very long baseline interferometry (VLBI) observations of relativistic jets outflowing from active galactic nuclei gives us direct information about jet width rjet(l) dependence on the distance l 'central engine'. Being missing link previous works, this relation opens possibility determining internal structure a jet. In article, we consider submerged an external medium with finite gas pressure Pext. Neither magnetic field nor infinitely thin current sheet will be assumed....

It was as early the 1980s that A V Gurevich and his group proposed a theory to explain magnetosphere of radio pulsars mechanism by which they produce coherent emission. The has been sharply criticized is currently rarely mentioned when discussing observational properties pulsars, even though all criticisms were in their time disproven most thorough detailed manner. Recent results show more conclusively no internal inconsistencies. New data also demonstrate validity basic conclusions theory....

Abstract Although fifty years have passed since the discovery of radio pulsars, there is still no satisfactory understanding how these amazing objects operate. While has been significant progress in basic properties as yet consensus on key issues, such nature coherent emission or conversion mechanism electromagnetic energy pulsar wind into particle energy. In this review, we present main theoretical results magnetosphere neutron stars. We formulate a number apparently simple questions, which...

ABSTRACT At present, there is no direct information about evolution of inclination angle χ between magnetic and rotational axes in radio pulsars. As to theoretical models pulsar evolution, they predict both the alignment, i.e. 0°, its counter-alignment, 90°. In this paper, we demonstrate that statistics interpulse pulsars can give us key test solve alignment/counter-alignment problem as number orthogonal (χ ≈ 90°) drastically depends on trajectory.

At present, there is no doubt that relativistic jets observed in active galactic nuclei pass from highly magnetized to weakly stage, which as a break the dependence on their width $d_{\rm jet}(z)$ distance $z$ central engine. In this paper, we discuss possibility of observing another break, should be located at shorter distances. The position can associated with region formation dense core near jet axis was predicted both analytically and numerically more than decade ago, but has not yet...

We demonstrate that the 1D cylindrical version of Grad-Shafranov equation is more rich than classical self-similar ones, and suitable for astrophysical jets we observe. In particular, it allows us to describe central (and, hence, most energetic) part flow. Both relativistic non-relativistic versions are discussed. It shown taking into account finite pressure external media one can determine magnetic flux within core. found as well flows which magnetically dominated near origin solution be...

A laboratory simulation of astrophysical processes is one the intensively developed areas plasma physics. new series experiments has been launched recently on focus type facility in NRC Kurchatov Institute. The main goal to study mechanisms jet stabilization, due which it can propagate at distances much greater than their transverse dimensions. with stationary gas filling revealed regimes a narrowly collimated was formed, head no wider several centimeters propagation up 100[Formula: see...

At present, there are theoretical models of radio pulsar evolution which predict both the alignment, i.e., inclination angle $χ$ between magnetic and rotational axes to $0^{\circ}$, its counter-alignment, $90^{\circ}$. same time, well describe distribution on $P$-$\dot P$ diagram. For this reason, up now it was impossible determine braking mechanisms since rather difficult estimate basis observation. In paper we demonstrate that statistics interpulse pulsars can give us key solve...