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Galactic cosmic rays are widely believed to be accelerated in expanding shock waves initiated by supernova explosions. The theory of diffusive shock acceleration of cosmic rays is now well established, but two fundamental questions remain…

Astrophysics · Physics 2008-07-25 Vincent Tatischeff

In this review, we examine particle transport in strongly turbulent three-dimensional (3D) magnetized plasmas, characterized by intense (large-amplitude) magnetic field fluctuations. Such environments naturally give rise to a network of…

Plasma Physics · Physics 2025-08-11 Heinz Isliker , Loukas Vlahos

The physics of particle acceleration in turbulent plasmas is a topic of broad interest, which is making rapid progress thanks to dedicated, large-scale numerical experiments. The first part of this paper presents an effective theory of…

Plasma Physics · Physics 2025-07-08 M. Lemoine

Estimating the cosmic-ray acceleration efficiency $ \epsilon $ in supernova remnants (SNRs) through observations is a challenging task in general. Based on the Rankine-Hugoniot shock conditions, we find an anticorrelation between $ \epsilon…

High Energy Astrophysical Phenomena · Physics 2018-12-21 Yiran Zhang , Siming Liu

Owing to the complexity of turbulent magnetic fields, modeling the diffusion of cosmic rays is challenging. Based on the current understanding of anisotropic magnetohydrodynamic (MHD) turbulence, we use test particles to examine the cosmic…

Astrophysics of Galaxies · Physics 2022-02-16 Yue Hu , A. Lazarian , Siyao Xu

A correct description of cosmic-ray (CR) diffusion in turbulent plasma is essential for many astrophysical and heliospheric problems. This paper aims to present physical diffusion behavior of CRs in actual turbulent magnetic fields, model…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Siyao Xu , Huirong Yan

Diffusive shock acceleration at collisionless shocks remains the most likely process for accelerating particles in a variety of astrophysical sources. While the standard prediction for strong shocks is that the spectrum of accelerated…

High Energy Astrophysical Phenomena · Physics 2025-12-15 Pierre Cristofari , Pasquale Blasi , Damiano Caprioli

The present paper is the last of a series studying the first-order Fermi acceleration processes at relativistic shock waves with the method of Monte Carlo simulations applied to shocks propagating in realistically modeled turbulent magnetic…

Astrophysics · Physics 2008-11-26 Jacek Niemiec , Michal Ostrowski , Martin Pohl

The diffusive motion of charged particles in synthetic magnetic turbulence with different properties is investigated by using numerical simulations with unprecedented dynamical range, which allow us to ensure that both the inertial range…

High Energy Astrophysical Phenomena · Physics 2020-11-24 Andrej Dundovic , Oreste Pezzi , Pasquale Blasi , Carmelo Evoli , William H. Matthaeus

Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Gilles Ferrand , Rebecca J. Danos , Andreas Shalchi , Samar Safi-Harb , Paul Edmon , Peter Mendygral

A generalized Fokker-Planck equation is derived to describe particle kinetics in specific situations when the probability transition function (PTF) has a long tail in momentum space. The equation is valid for an arbitrary value of the…

Statistical Mechanics · Physics 2011-08-15 A. A. Dubinova , S. A. Trigger

Diffusion of cosmic rays (CRs) is the key process of understanding their propagation and acceleration. We employ the description of spatial separation of magnetic field lines in MHD turbulence in Lazarian & Vishniac (1999) to quantify the…

High Energy Astrophysical Phenomena · Physics 2016-12-21 A. Lazarian , Huirong Yan

We investigate shock acceleration in a realistic astrophysical environment with density inhomogeneities. The turbulence induced by the interaction of the shock precursor with upstream density fluctuations amplifies both upstream and…

High Energy Astrophysical Phenomena · Physics 2022-02-02 Siyao Xu , Alex Lazarian

What are the mechanisms of particle acceleration and radiation, as well as magnetic field build up and decay in relativistic shocks are open questions with important implications to various phenomena in high energy astrophysics. While the…

High Energy Astrophysical Phenomena · Physics 2016-06-06 Evgeny V. Derishev , Tsvi Piran

We discuss the physics of stochastic particle acceleration in relativistic magnetohydrodynamic (MHD) turbulence, combining numerical simulations of test-particle acceleration in synthetic wave turbulence spectra with detailed analytical…

High Energy Astrophysical Phenomena · Physics 2020-07-06 Camilia Demidem , Martin Lemoine , Fabien Casse

We present results from a fully relativistic Monte Carlo simulation of diffusive shock acceleration (DSA) in unmodified (i.e., test-particle) shocks. The computer code uses a single algorithmic sequence to smoothly span the range from…

Astrophysics · Physics 2007-05-23 Donald C. Ellison

Relativistic collisionless shocks are associated with efficient particle acceleration when propagating into weakly magnetized homogeneous media; as the magnetization increases, particle acceleration becomes suppressed. We demonstrate that…

High Energy Astrophysical Phenomena · Physics 2023-04-26 Camilia Demidem , Joonas Nättilä , Alexandra Veledina

The efficiency of particle acceleration at shock waves in relativistic, magnetized astrophysical outflows is a debated topic with far-reaching implications. Here, for the first time, we study the impact of turbulence in the pre-shock…

High Energy Astrophysical Phenomena · Physics 2023-07-06 Virginia Bresci , Martin Lemoine , Laurent Gremillet

The theory of particle acceleration at shock fronts is briefly reviewed, with special emphasis on the production of the particles responsible for the nonthermal emission from blazars. The flat radio/IR spectra of these sources cannot be…

Astrophysics · Physics 2007-05-23 J. G. Kirk

The highly amplified magnetic fields suggested by observations of some supernova remnant (SNR) shells are most likely an intrinsic part of efficient particle acceleration by shocks. This strong turbulence, which may result from cosmic ray…

Astrophysics · Physics 2009-11-13 Andrey E. Vladimirov , Andrei M. Bykov , Donald C. Ellison