50 research outputs found
Quasi-linear diffusion driving the synchrotron emission in active galactic nuclei
We study the role of the quasi-linear diffusion (QLD) in producing X-ray
emission by means of ultra-relativistic electrons in AGN magnetospheric flows.
We examined two regions: (a) an area close to the black hole and (b) the outer
magnetosphere. The synchrotron emission has been studied for ultra-relativistic
electrons and was shown that the QLD generates the soft and hard X-rays, close
to the black hole and on the light cylinder scales respectively. By considering
the cyclotron instability, we show that despite the short synchrotron cooling
timescales, the cyclotron modes excite transverse and longitudinal-transversal
waves. On the other hand, it is demonstrated that the synchrotron reaction
force and a force responsible for the conservation of the adiabatic invariant
tend to decrease the pitch angles, whereas the diffusion, that pushes back on
electrons by means of the aforementioned waves, tends to increase the pitch
angles. By examining the quasi-stationary state, we investigate a regime in
which these two processes are balanced and a non-vanishing value of pitch
angles is created.Comment: 4 pages, 3 figure
Development of Kolmogorov spectrum in the pulsar radio emission
It is shown that the scattering of electromagnetic waves by Langmuir ones
taking into the account the electric drift motion of particles, is the most
intense nonlinear process and should be responsible for the formation of
radiation spectrum of radio pulsars. Performed analysis indicates that in the
case of existence of inertial interval formation of stationary spectra is
possible. Analysis of linear mechanisms of wave generation and silk allows to
conclude that only possible stationary solution has spectral index . Obtained spectrum is in good agreement with observational data.Comment: 12 pages, Astronomy Rep. (accepted
On the very high energy (>25GeV) pulsed emission in the Crab pulsar
We have examined the recently detected very high energy (VHE) pulsed
radiation from the Crab pulsar. According to the observational evidence, the
observed emission (>25GeV) peaks at the same phase with the optical spectrum.
Considering the cyclotron instability, we show that the pitch angle becomes
non-vanishing leading to the efficient synchrotron mechanism near the light
cylinder surface. The corresponding spectral index of the emission equals -1/2.
By studying the inverse Compton scattering and the curvature radiation, it is
argued that the aforementioned mechanisms do not contribute to the VHE
radiation detected by MAGIC.Comment: 11 pages, 1 figur
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
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
On the nature of radio pulsars with long periods
It is shown that the drift waves near the light cylinder can cause the
modulation of the emission with periods of the order several seconds. These
periods explain the intervals between successive pulses observed in "magnetars"
and radio pulsars with long periods. The model under consideration makes it
possible to calculate the real rotation periods of the host neutron stars. They
are less than 1 sec for the investigated objects. The magnetic fields at the
surface of the neutron star of the order 10^(11)-10^(13) G and equal to the
usual fields for known radio pulsarsComment: 18 pages, 4 figure