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We investigate the acceleration of charged particles (both electrons and protons) at collisionless shocks predicted to exist in the vicinity of solar flares. The existence of standing termination shocks has been examined by flare models and…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Fan Guo , Joe Giacalone

The question of the origin of ultra-high-energy cosmic rays at relativistic shock waves is discussed in the light of results of recent Monte Carlo studies of the first-order Fermi particle acceleration (Niemiec & Ostrowski 2006, Niemiec et…

Astrophysics · Physics 2007-05-31 Jacek Niemiec , Michal Ostrowski , Martin Pohl

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

In this paper, the acceleration of particles in astrophysical sources by the Fermi mechanism is revisited under the assumption of Lorentz invariance violation (LIV). We calculate the energy spectrum and the acceleration time of particles…

High Energy Astrophysical Phenomena · Physics 2025-07-10 Matheus Duarte , Vitor de Souza

In this chapter, we review some features of particle acceleration in astrophysical jets. We begin by describing four observational results relating to the topic, with particular emphasis on jets in active galactic nuclei and parallels…

High Energy Astrophysical Phenomena · Physics 2020-11-11 James Matthews , Anthony Bell , Katherine Blundell

In this paper we establish a formalism for the computation of observables due to acceleration-induced particle physics processes. General expressions for the transition rate, multiplicity, power, spectra, and displacement law of particles…

General Relativity and Quantum Cosmology · Physics 2015-07-16 Morgan H. Lynch

Energetic particles in a turbulent medium can be subject to second-order Fermi acceleration due to scattering on moving plasma waves. This mechanism leads to growing particle momentum dispersion and, at the same time, increases the mean…

Astrophysics · Physics 2011-05-23 M. Ostrowski , G. Siemieniec-Oziȩbło

A simplified model of particle transport at a quasiparallel one-dimensional collisionless shock is suggested. In this model the MHD-turbulence behind the shock is dominated by a circularly polarized, large amplitude Alfv\'en wave originated…

Astrophysics · Physics 2008-11-26 M. A. Malkov

We investigate the impact of magnetic fields and diffusion mechanisms on the energy spectra of particles accelerated via diffusive shock acceleration. We analyse magnetised shock jump conditions and demonstrate how magnetisation and angular…

High Energy Astrophysical Phenomena · Physics 2026-01-01 Anshuman Verma , Saksham Chandna , Divyansh Tripathi , Ritam Mallick

We study the classical and quantum dynamics of a Fermi accelerator realized by an atom bouncing off a modulated atomic mirror. We find that in a window of the modulation amplitude dynamical localization occurs in both position and momentum.…

Quantum Physics · Physics 2009-10-31 Farhan Saif , Iwo Bialynicki-Birula , Mauro Fortunato , Wolfgang P. Schleich

This review presents the fundamentals of the particle acceleration processes active in interstellar medium (ISM), which are essentially based on the so-called Fermi mechanism theory. More specifically, the review presents here in more…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Dejan Urošević , Bojan Arbutina , Dušan Onić

Cosmic rays are deemed to be generated by a process known as ``Fermi acceleration", in which charged particles scatter against magnetic fluctuations in astrophysical plasmas. The process itself is however universal, has both classical and…

This paper presents numerical simulations of test particle Fermi acceleration at relativistic shocks of Lorentz factor Gamma_sh = 2-60, using a realistic downstream magnetic structure obtained from the shock jump conditions. The upstream…

Astrophysics · Physics 2009-11-13 Martin Lemoine , Benoit Revenu

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

Magnetic reconnection drives multi-species particle acceleration broadly in space and astrophysics. We perform the first 3D hybrid simulations (fluid electrons, kinetic ions) that contain sufficient scale separation to produce nonthermal…

Solar and Stellar Astrophysics · Physics 2024-01-31 Qile Zhang , Fan Guo , William Daughton , Hui Li , Ari Le , Tai Phan , Mihir Desai

Using field theoretic renormalization, an MBE-type growth process with an obliquely incident influx of atoms is examined. The projection of the beam on the substrate plane selects a "parallel" direction, with rotational invariance…

Statistical Mechanics · Physics 2007-05-23 B. Schmittmann , Gunnar Pruessner , Hans-Karl Janssen

We calculate the first order maximal acceleration corrections to the classical electrodynamics of a particle in external electromagnetic fields. These include additional dissipation terms, the presence of a critical electric field, a…

High Energy Physics - Theory · Physics 2007-05-23 A. Feoli , G. Lambiase , G. Papini , G. Scarpetta

We investigate shock waves in the unitary Fermi gas by using the zero-temperature equations of superfluid hydrodynamics. We obtain analytical solutions for the dynamics of a localized perturbation of the uniform gas. These supersonic bright…

Quantum Gases · Physics 2011-11-11 Luca Salasnich

We study stochastic acceleration models for the Fermi bubbles. Turbulence is excited just behind the shock front via Kelvin--Helmholtz, Rayleigh--Taylor, or Richtmyer--Meshkov instabilities, and plasma particles are continuously accelerated…

High Energy Astrophysical Phenomena · Physics 2015-11-10 Kento Sasaki , Katsuaki Asano , Toshio Terasawa

We determine the asymptotic speed of the first-passage percolation process on some ladder-like graphs (or width-2 stretches) when the times associated with different edges are independent and exponentially distributed but not necessarily…

Probability · Mathematics 2011-02-24 Henrik Renlund