Related papers: Particle Acceleration in Shearing Flows: Efficienc…
We discuss a representative selection of particle acceleration mechanisms believed to be operating in Active Galactic Nuclei. Starting from direct electrostatic field acceleration in the vicinity of the black hole up to Fermi-type particle…
In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active…
Context. Converging flows with strong magnetic fields of different polarity can accelerate particles through magnetic reconnection. If the particle mean free path is longer than the reconnection layer is thick, but much shorter than the…
The acceleration of charged particles, producing collimated mono-energetic beams, over short distances holds the promise to offer new tools in medicine and diagnostics. Here, we consider a possible mechanism for accelerating protons to high…
In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the…
We consider the acceleration of charged particles at the ultra-relativistic shocks, with Lorentz factors \Gamma_s >> 1 relative to the upstream medium, arising in relativistic fireball models of gamma-ray bursts (GRBs). We show that for…
Astrophysical jets, launched from the immediate vicinity of accreting black holes, carry away large amounts of power in a form of bulk kinetic energy of jet particles and electromagnetic flux. Here we consider a simple analytical model for…
The source of high-energy protons (>500 MeV) responsible for the so-called ground level enhancements (GLEs) remains an open question in solar physics. One of the candidates is a shock wave driven by a coronal mass ejection, which is thought…
We present numerical simulations of axisymmetric, magnetically driven relativistic jets. To eliminate the dissipative effects induced by a free boundary with an ambient medium we assume that the flow is confined by a rigid wall of a…
A property common to several different astrophysical sources of high-energy gamma-rays is the presence of bulk motion at relativistic speed. The intrinsic spectra of the nonthermal radiating particles also show interesting similarities,…
Stochastic acceleration of electrons and protons by waves propagating parallel to the large scale magnetic fields of magnetized plasmas is studied with emphasis on the feasibility of accelerating particles from a thermal background to…
The process of cosmic ray acceleration up to energies in excess of $10^{20}$ eV at relativistic shock waves with large Lorentz factors, $\Gamma \gg 1$ requires $\sim \Gamma^2$ particle energy gains at single reflections from the shock (cf.…
Matter falling onto black holes, {also called} accretion discs, emit intense high-energy radiation. Accretion discs during {hard to hard intermediate} spectral states also emit bipolar outflows. Radiation drag was supposed to impose the…
Using 2.5-dimensional Particle-in-Cell simulations, we study the kinetic physics of relativistic shear flow boundary in collisionless electron-positron (e+e-) plasmas. We find efficient magnetic field generation and particle energization at…
A short overview of the theory of acceleration of thin foils driven by the radiation pressure of superintense lasers is presented. A simple criterion for radiation pressure dominance at intensities around $5 \times 10^{20} \mbox{W cm}^{-2}$…
Identified is a set of ballpark parameters for laser, plasma, and accelerator technologies that are defined for accelerated electron energies reaching as high as PeV. These parameters are carved out from the scaling laws that govern the…
Radiation pressure acceleration (RPA) is a highly efficient mechanism of laser-driven ion acceleration, with with near complete transfer of the laser energy to the ions in the relativistic regime. However, there is a fundamental limit on…
We report a stochastic mechanism of particle acceleration from first principles in an environment having properties like those of Radio Lobes in AGNs. We show that energies $\sim 10^{20}$ eV are reached in $\sim 10^6$ years for protons. Our…
We consider the acceleration of particles (protons) in a plasma clot by an induced field which appears due to the dissolving of the clot. The mechanism of this acceleration is based on a model where the clot consists of double flat moving…
Hot accretion flows contain collisionless plasmas that are believed to be capable of accelerating particles to very high energies, as a result of turbulence generated by the magnetorotational instability (MRI). We conduct unstratified…