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Recently a new transport theory of cosmic rays in magnetized space plasmas extending the quasilinear approximation to the particle orbit has been developed for the case of an axisymmetric incompressible magnetic turbulence. Here we…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Sabrina Casanova , Reinhard Schlickeiser

Particles crossing repeatedly the surface of a shock wave can be energized by first order Fermi acceleration. The linear theory is successful in describing the acceleration process as long as the pressure of the accelerated particles…

Astrophysics · Physics 2009-11-10 Pasquale Blasi

In high-energy astrophysics, interpreting observed spectra hinges on understanding the competition between energy gains and radiative losses. To progress along these lines, we report on particle-in-cell simulations of particle acceleration…

High Energy Astrophysical Phenomena · Physics 2025-12-17 M. Lemoine , V. Bresci , L. Gremillet

This review aims at providing an up-to-date status and a general introduction to the subject of the numerical study of energetic particle acceleration and transport in turbulent astrophysical flows. The subject is also complemented by a…

High Energy Astrophysical Phenomena · Physics 2020-02-26 A. Marcowith , G. Ferrand , M. Grech , Z. Meliani , I. Plotnikov , R. Walder

We numerically study the diffusion and scattering of cosmic rays (CRs) together with their acceleration processes in the framework of the modern understanding of magnetohydrodynamic (MHD) turbulence. Based on the properties of compressible…

High Energy Astrophysical Phenomena · Physics 2023-11-17 Nana Gao , Jianfu Zhang

We propose a nonlinear self-consistent model of the turbulent non-resonant particle acceleration in solar flares. We simulate temporal evolution of the spectra of charged particles accelerated by strong long-wavelength MHD turbulence taking…

Solar and Stellar Astrophysics · Physics 2009-11-13 A. M. Bykov , G. D. Fleishman

It is not fully understood how electromagnetic waves propagate through plasma density fluctuations when the size of the fluctuations is comparable with the wavelength of the incident radiation. In this paper, the perturbing effect of a…

Plasma Physics · Physics 2016-09-21 Alf Köhn , Eberhard Holzhauer , Jarrod Leddy , Matthew B Thomas , Roddy G L Vann

The shock waves produce relativistic particles via the diffusive shock acceleration (DSA) mechanism. Among various circumstances, fast acceleration has been expected for perpendicular shocks. We investigate the acceleration time and the…

High Energy Astrophysical Phenomena · Physics 2020-07-15 Shoma F. Kamijima , Yutaka Ohira , Ryo Yamazaki

The propagation of light in a scattering medium is described as the motion of a special kind of a Brownian particle on which the fluctuating forces act only perpendicular to its velocity. This enforces strictly and dynamically the…

Disordered Systems and Neural Networks · Physics 2009-10-31 S. Anantha Ramakrishna , N. Kumar

We investigate test-particle diffusion in dynamical turbulence based on a numerical approach presented before. For the turbulence we employ the nonlinear anisotropic dynamical turbulence model which takes into account wave propagation…

High Energy Astrophysical Phenomena · Physics 2016-09-28 Martin Heusen , Andreas Shalchi

The diffusions and anomalous diffusions of charged particles in the plateau regime of toroidal plasma with a Maxwellian velocity distribution are studied. The transport theory of plasma is discussed under the toroidal coordinate system and…

Plasma Physics · Physics 2021-12-28 Wang Hong , Du Jiulin

In the subset of luminous, early-type stars with strong, large-scale magnetic fields and moderate to rapid rotation, material from the star's radiatively driven stellar wind outflow becomes trapped by closed magnetic loops, forming a…

Solar and Stellar Astrophysics · Physics 2017-12-27 Stanley P. Owocki , Steven R. Cranmer

We present simulations of magnetized astrophysical shocks taking into account the interplay between the thermal plasma of the shock and supra-thermal particles. Such interaction is depicted by combining a grid-based magneto-hydrodynamics…

High Energy Astrophysical Phenomena · Physics 2017-10-02 Allard Jan van Marle , Fabien Casse , Alexandre Marcowith

It is well known that magnetic fields constrain motions of charged particles, impeding the diffusion of charged particles perpendicular to magnetic field direction. This modification of transport processes is of vital importance for a wide…

Astrophysics of Galaxies · Physics 2015-03-19 A. Lazarian

The recent discoveries in the theory of diffusive shock acceleration (DSA) that stem from first-principle kinetic plasma simulations are discussed. When ion acceleration is efficient, the back-reaction of non-thermal particles and…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Damiano Caprioli , Colby Haggerty , Pasquale Blasi

Cosmic ray propagation is diffusive because of pitch angle scattering by waves. We demonstrate that if the high-amplitude magnetohydrodynamic turbulence with $\tilde B/\langle B\rangle \sim 1$ is present on top of the mean field gradient,…

High Energy Astrophysical Phenomena · Physics 2015-09-30 Mikhail V. Medvedev , Viktor V. Medvedev

Energetic particles spectra at interplanetary shocks often exhibit a power law within a narrow momentum range softening at higher energy. We introduce a transport equation accounting for particle acceleration and escape with diffusion…

High Energy Astrophysical Phenomena · Physics 2021-03-10 Federico Fraschetti

Collisionless, magnetized turbulence offers a promising framework for the generation of non-thermal high-energy particles in various astrophysical sites. Yet, the detailed mechanism that governs particle acceleration has remained subject to…

High Energy Astrophysical Phenomena · Physics 2022-08-17 Virginia Bresci , Martin Lemoine , Laurent Gremillet , Luca Comisso , Lorenzo Sironi , Camilia Demidem

In this work we investigate particle acceleration in supernova remnant shocks within a semi-analytical formalism which self-consistently accounts for particle acceleration, amplification of the magnetic field via streaming instability and…

High Energy Astrophysical Phenomena · Physics 2011-03-25 Damiano Caprioli

We study the linear evolution of small perturbations in self-gravitating fluid systems with magnetic fields. We consider wave-like perturbations to nonuniform filamentary and sheet-like hydrostatic equilibria in the presence of a uniform…

Astrophysics · Physics 2015-06-24 Curtis S. Gehman , Fred C. Adams , Richard Watkins
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