Related papers: Relativistic Blastwaves and Synchrotron Emission
For an expanding spherical relativistic shock, we derive relations between the parameters of downstream emitting zone and the quantities measured by a distant observer. These relations are formulated in terms of dimensionless effective…
We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic jet propagating into an unmagnetized plasma. Strong magnetic fields generated in the trailing jet shock lead to transverse…
We present results of a detailed numerical study and theoretical analysis of the dynamics of internal shocks in relativistic jets and the non-thermal flares associated with these shocks. In our model internal shocks result from collisions…
The probability that a particle, crossing the shock along a given direction, be reflected backwards along another direction, was shown to be the key element in determining the spectrum of non--thermal particles accelerated via the Fermi…
The author is developing a numerical code with thousands of emission zones to simulate the time-dependent multi-waveband emission from blazars. The code is based on a model in which turbulent plasma flowing at a relativistic speed down a…
We study a type of particle acceleration that operates via neutron-proton conversion in inelastic nuclear collisions. This mechanism can be expected for relativistic shocks at subphotospheres if relativistic outflows contain neutrons. Using…
Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle…
Gamma-Ray Bursts are good candidates of the ``bottom up'' scenario for the generation of the UHE Cosmic Rays. In the most discussed model of GRBs, namely the ``fireball'' model, a highly relativistic shock forms and seems capable of…
We review the present status of the cosmic ray acceleration theory in mildly relativistic shock waves. Due to the involved substantial particle anisotropies analytical methods can tackle only simple situations involving weakly turbulent…
First order Fermi acceleration at astrophysical shocks is often invoked as a mechanism for the generation of non-thermal particles. This mechanism is especially simple in the approximation that the accelerated particles behave like test…
Re-brightening bumps are frequently observed in gamma-ray burst (GRB) afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has…
Cosmic rays, thermal gas and magnetic fields in FRII radio cavities are assumed to come entirely from winds flowing from just behind the jet shocks. Combining analytic and computational methods, it is shown that the computed radio-electron…
Monte Carlo techniques are used to model nonlinear particle acceleration in parallel collisionless shocks of various speeds, including mildly relativistic ones. When the acceleration is efficient, the backreaction of accelerated particles…
All galaxies without a radio-loud AGN follow a tight correlation between their global FIR and radio synchrotron luminosities, which is believed to be ultimately the result of the formation of massive stars. Two colliding pairs of galaxies,…
Relativistic reconnection has been invoked as a mechanism for particle acceleration in numerous astrophysical systems. According to idealised analytical models reconnection produces a bulk relativistic outflow emerging from the reconnection…
The synchrotron emission observed from many astrophysical objects is commonly modelled to arise from relativistic electrons in an emission region occupied by a spatially homogeneous, but tangled magnetic field. However, we know that…
We model the diffusive shock acceleration of particles in a system of two colliding shock waves and present a method to solve the time-dependent problem analytically in the test-particle approximation and high energy limit. In particular,…
The broad-band spectral distributions of non-thermal sources, such as those of several known blazars, are well described by a log-parabolic fit. The second degree term in these fits measures the curvature in the spectrum. In this paper we…
We present a general formulation of special-relativistic magnetohydrodynamics and derive exact radially self-similar solutions for axisymmetric outflows from strongly magnetized, rotating compact objects. We generalize previous work by…
Gamma-ray bursts are generally considered to be the result of internal shocks generated in an inhomogeneous relativistic outflow that arises from a fireball. In such shocks, the Fermi acceleration of protons is naturally expected to be at…