Centrifugally induced curvature drift instability in AGN

We investigate the centrifugally driven curvature drift instability to study how field lines twist close to the light cylinder surface of an AGN, through which the free motion of AGN winds can be monitored. By studying the dynamics of the relativistic MHD flow close to the light cylinder surface, we derive and solve analytically the dispersion relation of the instability by applying a single particle approach based on the centrifugal acceleration. Considering the typical values of AGN winds, it is shown that the timescale of the curvature drift instability is far less than the accretion process timescale, indicating that the present instability is very efficient and might strongly influence processes in AGN plasmas.Comment: 4 pages, 5 figure

Heavy Quarkonia Spectroscopy

Recent experimental results on heavy quarkonia spectroscopy and decays are reviewed. In particular, new results are discussed on charmonium spin singlet states, bottomonium D-states, photon and hadronic transitions from heavy quarkonium states, and the unexplained narrow X(3872) state.Comment: 10 pages, 6 figures. Talk given at Heavy Quarks and Leptons 2004, San Juan, Puerto Rico, June 1-5, 200

Radio emission of magnetars driven by the quasi-linear diffusion

In this, paper we study the possibility of generation of electromagnetic waves in the magnetospheres of radio magnetars by means of the quasi-linear diffusion (QLD). Considering the magnetosphere composed of the so-called beam and the plasma components respectively, we argue that the frozen-in condition will inevitably lead to the generation of the unstable cyclotron modes. These modes, via the QLD, will in turn influence the particle distribution function, leading to certain values of the pitch angles, thus to an efficient synchrotron mechanism, producing radio photons. We show that for three known radio magnetars the QLD might be a realistic mechanism for producing photons in the radio band.Comment: 5 pages, 1 figur

Synchrotron emission driven by the Cherenkov-drift instability in active galactic nuclei

In the present paper we study generation of the synchrotron emission by means of the feedback of Cherenkov drift waves on the particle distribution via the diffusion process. It is shown that despite the efficient synchrotron losses the excited Cherenkov drift instability leads to the quasi-linear diffusion (QLD), effect of which is balanced by dissipation factors and as a result the pitch angles are prevented from damping, maintaining the corresponding synchrotron emission. The model is analyzed for a wide range of physical parameters and it is shown that the mechanism of QLD guarantees the generation of electromagnetic radiation from soft $X$-rays up to soft $\gamma$-rays, strongly correlated with Cherenkov drift emission ranging from IR up to UV energy domains.Comment: 8 pages, 3 figure

On the mechanism of the pulsed high energy emission from the pulsar PSR B1509-58

We investigate the high-energy (HE) ($<1$GeV) emission from the pulsar PSR B1509-58 and its relation to the radio emission in the 1.4GHz frequency band. The role of the quasi-linear diffusion in producing the pulsed HE radiation is investigated. We show that by means of the cyclotron instability the relatively low frequency waves excite, which due to the diffusion process influence the particle distribution function and switch on the synchrotron emission mechanism. We argue that the coincidence of HE main peak and the radio pulse is a direct consequence of the fact that the high and low frequency radiation is produced simultaneously in a local area of the pulsar magnetosphere. In the paper we also consider the absence of the radio counter pulse and explain this fact.Comment: 5 pages, 2 figure

Commutator automorphisms of formal power series rings

For a big class of commutative rings R every continuous R-automorphism of R[[X_1,...,X_n]] with the identity linear part is in the commutator subgroup of Aut(R[[X_1,...,X_n]]). An explicit bound for the number of the involved commutators and a K-theoretic interpretation of this result are provided.Comment: to appear in Proc. Amer. Math. So

Self-heating in kinematically complex magnetohydrodynamic flows

The non-modal self-heating mechanism driven by the velocity shear in kinematically complex magnetohydrodynamic (MHD) plasma flows is considered. The study is based on the full set of MHD equations including dissipative terms. The equations are linearized and unstable modes in the flow are looked for. Two different cases are specified and studied: (a) the instability related to an exponential evolution of the wave vector; and (b) the parametric instability, which takes place when the components of the wave vector evolve in time periodically. By examining the dissipative terms, it is shown that the self-heating rate provided by viscous damping is of the same order of magnitude as that due to the magnetic resistivity. It is found that the heating efficiency of the exponential instability is higher than that of the parametric instability.Comment: 7 pages, 5 figure

On the spectrum of the pulsed gamma-ray emission from 10MeV to 400GeV of the Crab pulsar

In the present paper a self-consistent theory, interpreting the VERITAS observations of the very high energy pulsed emission from the Crab pulsar is considered. The photon spectrum between 10MeV and 400GeV can be described by two power-law functions with the spectral indexes equal to 2 and 3.8. The source of the pulsed emission above 10MeV is assumed to be the synchrotron radiation, which is generated near the light cylinder during the quasi-linear stage of the cyclotron instability. The emitting particles are the primary beam electrons with the Lorentz factors up to $10^{9}$. Such high energies by beam particles is supposed to be reached due to Landau damping of the centrifugally induced Langmuir waves. This mechanism provides simultaneous generation of low (radio) and high energy (10MeV-400GeV) emission on the light cylinder scales, in one location of the pulsar magnetosphere.Comment: 5 page

Extremely efficient Zevatron in rotating AGN magnetospheres

A novel model of particle acceleration in the magnetospheres of rotating active galactic nuclei (AGN) is constructed.The particle energies may be boosted up to $10^{21}$eV in a two step mechanism: In the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. In the second stage, the electrostatic energy is transferred to particle kinetic energy via Landau damping made possible by rapid "Langmuir collapse". The time-scale for parametric pumping of Langmuir waves turns out to be small compared to the kinematic time-scale, indicating high efficiency of the first process. The second process of "Langmuir collapse" - the creation of caverns or low density regions - also happens rapidly for the characteristic parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate conditions for transferring electric energy to boost up already high particle energies to much higher values. It is further shown that various energy loss mechanism are relatively weak, and do not impose any significant constraints on maximum achievable energies.Comment: 7 page

Parametric mechanism of the rotation energy pumping by a relativistic plasma

An investigation of the kinematics of a plasma stream rotating in the pulsar magnetosphere is presented. On the basis of an exact set of equations describing the behavior of the plasma stream, the increment of the instability is obtained, and the possible relevance of this approach for the understanding of the pulsar rotation energy pumping mechanism is discussed.Comment: 6 pages 1 figur