Nino Chkheidze

Ultra High Energy Electrons Powered by Pulsar Rotation

A new mechanism of particle acceleration, driven by the rotational slow down of the Crab pulsar, is explored. The rotation, through the time dependent centrifugal force, can efficiently excite unstable Langmuir waves in the electron-positron (hereafter e±) plasma of the star magnetosphere. These waves, then, Landau damp on electrons accelerating them in the process. The net transfer of energy is optimal when the wave growth and the Landau damping times are comparable and are both very short compared to the star rotation time. We show, by detailed calculations, that these are precisely the conditions for the parameters of the Crab pulsar. This highly efficient route for energy transfer allows the electrons in the primary beam to be catapulted to multiple TeV (~ 100 TeV) and even PeV energy domain. It is expected that the proposed mechanism may, unravel the puzzle of the origin of ultra high energy cosmic ray electrons.

ON THE VERY HIGH ENERGY SPECTRUM OF THE CRAB PULSAR

In the present paper, we construct a self-consistent theory interpreting the observations from the MAGIC Cherenkov Telescope of the very high energy (VHE) pulsed emission from the Crab pulsar. In particular, on the basis of Vlasovs kinetic equation, we study the process of quasi-linear diffusion (QLD) developed by means of the cyclotron instability. This mechanism provides simultaneous generation of low (radio) and VHE (0.01-25 GeV) emission on light cylinder scales in one location of the pulsar magnetosphere. A different approach to the synchrotron emission is considered, giving the spectral index of the VHE emission ({beta} = 2) and the exponential cutoff energy (23 GeV) in good agreement with the observational data.

Millisecond newly born pulsars as efficient accelerators of electrons.

The newly born millisecond pulsars are investigated as possible energy sources for creating ultra-high energy electrons. The transfer of energy from the star rotation to high energy electrons takes place through the Landau damping of centrifugally driven (via a two stream instability) electrostatic Langmuir waves. Generated in the bulk magnetosphere plasma, such waves grow to high amplitudes, and then damp, very effectively, on relativistic electrons driving them to even higher energies. We show that the rate of transfer of energy is so efficient that no energy losses might affect the mechanism of particle acceleration; the electrons might achieve energies of the order of 1018 eV for parameters characteristic of a young star.

On the Spectrum of the Pulsed Gamma-Ray Emission of the Crab Pulsar from 10?MeV to 400 GeV

In the present paper, a self-consistent theory, interpreting VERITAS and the MAGIC observations of the very high-energy pulsed emission from the Crab pulsar, is considered. The photon spectrum between 10?MeV and 400?GeV can be described by two power-law functions with spectral indices of 2.0 and 3.8. The source of the pulsed emission above 10?MeV is assumed to be 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 Lorentz factors up to 109. Such high energies of beam particles can be reached due to Landau damping of the Langmuir waves in the light cylinder region.

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

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

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The plasma emission model of RBS1774

-rays up to soft

A possible mechanism for forming the radio emission spectrum of the Crab pulsar

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On high frequency Cherenkov-type radiation in pulsar magnetospheric electron-positron plasma

-rays, strongly correlated with Cherenkov drift emission ranging from IR up to UV energy domains.

Extremely efficient Zevatron in rotating AGN magnetospheres

We investigate the high-energy (<1 GeV) emission from the pulsar PSR B1509-58, and its relation to the radio emission in the 1.4-GHz frequency band. We investigate the role that quasi-linear diffusion plays in the production of pulsed high-energy radiation. We show that the relatively low-frequency waves are excited by cyclotron instability and, because of the diffusion process, this influences the particle distribution function and switches on the synchrotron emission mechanism. We argue that the coincidence of the high-energy main peak and the radio pulse is a direct consequence of the fact that both high- and low-frequency radiation are produced simultaneously in the local area of the pulsar magnetosphere. We also consider and explain the absence of the radio counter pulse.