Rotationally-driven VHE emission from the Vela pulsar

The recent detection of pulsed $\gamma$-ray emission from the Vela pulsar in the $\sim10$ to 100 GeV range by H.E.S.S. promises an important potential to probe into the very high energy (VHE) radiation mechanisms of pulsars. The recent detection of pulsed $\gamma$-ray emission from the Vela pulsar in the $\sim10$ to 100 GeV range by H.E.S.S. promises an important potential to probe into the very high energy (VHE) radiation mechanisms of pulsars. We analyze achievable particle energies in the magnetosphere of the Vela pulsar, and calculate the resultant emission properties. Inverse Compton up-scattering of thermal photons from the surface of the star is shown to lead a pulsed VHE contribution reaching into the TeV regime with spectral characteristics compatible with current findings. If confirmed by further observations this could be the second case where rotationally-driven processes turn out to be important to understand the VHE emission in young pulsars.Comment: 5 pages, 2 figure

Radio pulsars resonantly accelerating electrons

Based on the recently demonstrated resonant wave-wave process, it is shown that electrons can be accelerated to ultra-relativistic energies in the magnetospheres of radio pulsars. The energization occurs via the resonant interaction of the electron wave (described by a Klein-Gordon (KG) equation) moving in unison with an intense electromagnetic (EM) wave; the KG wave/particle continuously draws energy from EM. In a brief recapitulation of the general theory, the high energy (resonantly enhanced) electron states are investigated by solving the KG equation, minimally coupled to the EM field. The restricted class of solutions, that propagate in phase with EM radiation (functions only of $\zeta=\omega t-kz$), are explored to serve as a possible basis for the proposed electron energization in the radio pulsars. We show that the wave-wave resonant energization mechanism could be operative in a broad class of radio pulsars with periods ranging from milliseconds to the normal values ($\sim 1$ sec); it could drive the magnetospheric electrons to acquire energies from $100$s of TeVs (millisecond pulsars) to $10$ ZeVs (normal pulsars).Comment: 5 pages, 2 figure

On the fraction of particles involved in magneto-centrifugally generated ultra-high energy electrons in the Crab pulsar

The earthward journey of ultra high energy electrons ($\sim 600$ TeV) produced in the Pulsar atmosphere by Landau damping of magneto-centrifugally excited Langmuir waves (drawing energy form the rotational slowdown) on primary electrons, is charted. It is shown, that just as they escape the light cylinder zone, the ultra-high energy particles, interacting with the medium of the Crab nebula, rapidly loose their energy via the quantum synchrotron process, producing highly energetic gamma rays ~ $\sim 0.6$PeV. Interacting with the cosmic background radiation in the interstellar medium, only a tiny fraction of these ultra high energy photons (via the $\gamma\gamma$ channel) are, then transformed into electron-positron pairs. Detected flux of these photons imposes an upper limit on the fraction ($4\times 10^{-7}$) of the magnetospheric particles involved in the process of generation of ultra-high energy photons (up to $600$ TeV).Comment: 8 pages, 2 figure

On the reconstruction of a magnetosphere of pulsars nearby the light cylinder surface

A mechanism of generation of a toroidal component of large scale magnetic field, leading to the reconstruction of the pulsar magnetospheres is presented. In order to understand twisting of magnetic field lines, we investigate kinematics of a plasma stream rotating in the pulsar magnetosphere. Studying an exact set of equations describing the behavior of relativistic plasma flows, the increment of the curvature drift instability is derived, and estimated for $1s$ pulsars. It is shown that a new parametric mechanism is very efficient and can explain rotation energy pumping in the pulsar magnetospheres.Comment: 6 pages, 2 figure

Centrifugally driven electrostatic instability in extragalactic jets

The stability problem of the rotation induced electrostatic wave in extragalactic jets is presented. Solving a set of equations describing dynamics of a relativistic plasma flow of AGN jets, an expression of the instability rate has been derived and analyzed for typical values of AGNs. The growth rate was studied versus the wave length and the inclination angle and it has been found that the instability process is much efficient with respect to the accretion disk evolution, indicating high efficiency of the instability.Comment: 7 pages, 4 figure