Related papers: Particle Acceleration in an Evolving Network of Un…
The acceleration of energetic particles in astrophysical shear flows is analyzed. We show that in the presence of a non-relativistic gradual velocity shear, power law particle momentum distributions $f(p) \propto p^{-(3+\alpha)}$ may be…
The outflows from gamma ray bursts, active galactic nuclei and relativistic jets in general interact with the surrounding media through collisionless shocks. With three dimensional relativistic particle-in-cell simulations we investigate…
A mechanism of ultra-high energy cosmic ray acceleration in extragalactic radio sources, at the interface between the relativistic jet and the surrounding medium, is discussed as a supplement to the shock acceleration in `hot spots'. Due to…
We study the acceleration of ultra-high-energy cosmic rays (UHECRs) at FR-II radio galaxies by performing Monte Carlo simulations for the transport, scattering, and energy change of the CR particles injected into the time-evolving jet flows…
We analyze the dynamics of particles in two dimensions with constant speed and a stochastic switching angle dynamics defined by a correlated dichotomous Markov process (telegraph noise) plus Gaussian white noise. We study various cases of…
Current sheets (CSs) are preferred sites of magnetic reconnection and energy dissipation in collisionless astrophysical plasmas. Electric currents in them may be carried by both electrons and ions. In our prior theoretical studies of…
In-situ spacecraft observations recently suggested that the transport of energetic particles accelerated at heliospheric shocks can be anomalous, i.e. the mean square displacement can grow non-linearly in time. In particular, a new analysis…
The early acceleration of protons and electrons in the nonrelativistic collisionless shocks with three obliquities are investigated through 1D particle-in-cell simulations. In the simulations, the charged particles possessing a velocity of…
We propose a novel electron acceleration mechanism, which we call stochastic shock drift acceleration (SSDA), that extends the standard shock drift acceleration (SDA) for low-energy electrons at a quasi-perpendicular shock to include the…
Using bifurcation theory on a dynamical system simulating the interaction of a particle with an obliquely propagating wave in relativistic regimes, we demonstrate that uniform acceleration arises as a consequence of Hopf bifurcations of…
Heliospheric shocks are excellent systems for testing theories of particle acceleration in their environs. These generally fall into two classes: (1) interplanetary shocks that are linear in their ion acceleration characteristics, with the…
The chaotic diffusion for particles moving in a time dependent potential well is described by using two different procedures: (i) via direct evolution of the mapping describing the dynamics and ; (ii) by the solution of the diffusion…
Shear flows are naturally expected to occur in astrophysical environments and potential sites of continuous non-thermal Fermi-type particle acceleration. Here we investigate the efficiency of expanding relativistic outflows to facilitate…
Chandra's high resolution observations of radio galaxies require a revisit of the relevant electron acceleration processes. Although the diffusive shock particle acceleration model may explain spectra of spatially unresolved sources, it…
Fast particles are accelerated in astrophysical environments by a variety of processes. Acceleration in reconnection sites has attracted the attention of researchers recently. In this letter we analyze the energy distribution evolution of…
Due to Heisenberg's uncertainty principle, atomic electrons localized around the nucleus exhibit a characteristic momentum distribution that, in elements with high atomic number, remains significant up to relativistic values. Consequently,…
Colliding high energy hadrons either produce new particles or scatter elastically with their quantum numbers conserved and no other particles produced. We consider the latter case here. Although inelastic processes dominate at high…
We investigate the interaction of nonthermal ions (protons and nuclei) accelerated in an ultrarelativistic blastwave with the pre-existing magnetic field of the medium into which the blastwave propagates. While particle acceleration…
Shock acceleration is considered one of the most important mechanisms for the acceleration of astrophysical energetic particles. In this work, we calculate the trajectories of a large number of test charged particles accurately in a…
Two-dimensional particle simulations of a relativistic Harris current sheet of pair plasmashave demonstrated that the system is unstable to the relativistic drift kink instability (RDKI) and that a new kind of acceleration process takes…