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The rate at which particles are accelerated by the first-order Fermi mechanism in shocks depends on the angle, \teq{\Tbone}, that the upstream magnetic field makes with the shock normal. The greater the obliquity the greater the rate, and…

Astrophysics · Physics 2009-10-28 D. C. Ellison , M. G. Baring , F. C. Jones

We have developed a Monte Carlo technique for self-consistently calculating the hydrodynamic structure of oblique, steady-state shocks, together with the first-order Fermi acceleration process and associated non-thermal particle…

Astrophysics · Physics 2009-10-28 Donald C. Ellison , Matthew G. Baring , Frank C. Jones

We study the formation and dynamics of shock waves initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of shock waves mediated…

Quantum Gases · Physics 2019-10-03 Wen Wen , Tiankun Shui , Yafei Shan , Changping Zhu

We simulate the acceleration processes of collisionless particles in a shock structure with magnetohydrodynamical (MHD) fluctuations. The electromagnetic field is represented as a sum of MHD shock solution ($\Mag_0, \Ele_0$) and torsional…

Astrophysics · Physics 2009-11-13 Takayuki Muranushi , Shu-ichiro Inutsuka

This proceedings paper reports on the theoretical modelling of particle acceleration in magnetised turbulent plasmas. It briefly reviews some recent findings obtained from fully kinetic numerical simulations of large-amplitude, semi to…

High Energy Astrophysical Phenomena · Physics 2025-12-18 M. Lemoine

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

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,…

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

The mechanism of diffusive Fermi acceleration at collisionless plasma shock waves is widely invoked in astrophysics to explain the appearance of non-thermal particle populations in a variety of environments, including sites of cosmic ray…

Astrophysics · Physics 2007-05-23 Matthew G. Baring

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…

High Energy Astrophysical Phenomena · Physics 2019-04-17 F. -J. Kong , G. Qin , S. -S. Wu , L. -H. Zhang , H. -N. Wang , T. Chen , P. Sun

The acceleration of charged particles in magnetized plasmas is considered during turbulent multi-island magnetic reconnection. The particle acceleration model is constructed for an ensemble of islands which produce adiabatic compression of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Nicolas Bian , Eduard Kontar

A review of theoretical results on cosmic ray first-order Fermi acceleration at relativistic shock waves is presented, with recent results substantially changing the existing knowledge on these processes. In particular one can not expect…

Astrophysics · Physics 2011-11-10 M. Ostrowski

The momentum distribution of particles accelerated at strong non-relativistic shocks may be influenced by the spatial distribution of the flow speed around the shock. This phenomenon becomes evident in the cosmic-ray modified shock, where…

High Energy Astrophysical Phenomena · Physics 2024-08-14 O. Petruk , T. Kuzyo

Theoretical studies of cosmic ray particle acceleration in the first-order Fermi process at relativistic shocks are reviewed. At the beginning we discuss the acceleration processes acting at mildly relativistic shock waves. An essential…

Astrophysics · Physics 2007-05-23 Michal Ostrowski

A box model is used to study first order Fermi acceleration driven by magnetic reconnection. It is shown, at least in this simple model, that the spectral index of the accelerated particles is related to the total compression in the same…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Luke O'C. Drury

We present numerical modelling of particle acceleration at coronal shocks propagating through a streamer-like magnetic field by solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show…

Solar and Stellar Astrophysics · Physics 2019-09-25 Xiangliang Kong , Fan Guo , Yao Chen , Joe Giacalone

We examine the first order Fermi acceleration on the presumption that supernova remnant shocks cross ambient magnetic fields with various angles. These oblique shocks accelerate particles more efficiently than the parallel shocks and…

Astrophysics · Physics 2009-10-31 K. Kobayakawa , Y. S. Honda , T. Samura

We present a first-principles model of pitch-angle and energy distribution function evolution as particles are sequentially accelerated by multiple flare magnetic islands. Data from magnetohydrodynamic (MHD) simulations of an eruptive…

Solar and Stellar Astrophysics · Physics 2022-02-16 Silvina E. Guidoni , Judith T. Karpen , C. Richard DeVore

We derive a relativistically covariant (although not manifestly so) equation for the distribution function of particles accelerated at shocks, which applies also to extremely relativistic shocks, and arbitrarily anisotropic particle…

Astrophysics · Physics 2009-11-07 Mario Vietri

The process of cosmic ray first-order Fermi acceleration at relativistic shock waves is studied with the method of Monte Carlo simulations. The simulations are based on numerical integration of particle equations of motion in a turbulent…

Astrophysics · Physics 2009-11-10 Jacek Niemiec , Michal Ostrowski

Energetic particles are ubiquitous in space and astrophysical plasmas, and interplanetary shocks are widely regarded as one of the main particle accelerators in the heliosphere. Indeed, in-situ measurements typically show that energetic…

Solar and Stellar Astrophysics · Physics 2026-04-17 Giuseppe Prete , Gaetano Zimbardo , Silvia Perri