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Low frequency electromagnetic turbulence is generated in relativistically outflowing plasma that sweeps up particles from the surrounding environment. Electrons are energized by stochastic gyroresonant acceleration with the turbulence…

Astrophysics · Physics 2007-05-23 R. Schlickeiser , C. D. Dermer

Identifying the accelerators of Galactic cosmic ray protons (CRs) with energies up to a few PeV ($10^{15}$ eV) remains a theoretical and observational challenge. Supernova remnants (SNRs) represent strong candidates, as they provide…

High Energy Astrophysical Phenomena · Physics 2024-04-24 Rebecca Diesing

The increase in renewable energy sources (RESs), like wind or solar power, results in growing uncertainty also in transmission grids. This affects grid stability through fluctuating energy supply and an increased probability of overloaded…

Systems and Control · Electrical Eng. & Systems 2022-04-13 Rebecca Bauer , Tillmann Mühlpfordt , Nicole Ludwig , Veit Hagenmeyer

We explore the dynamics of active elements performing persistent random motion with fluctuating active speed and in the presence of translational noise in a $d$-dimensional harmonic trap, modeling active speed generation through an…

Statistical Mechanics · Physics 2025-02-18 Manish Patel , Amir Shee , Debasish Chaudhuri

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

Self-propelled particles can navigate complex environments, including viscous fluid interfaces with curved geometries. In this work, we study the emergent dynamics of a suspension of self-propelled particles confined to a stationary curved…

Fluid Dynamics · Physics 2026-04-17 Yuzhu Chen , Vishal P. Patil , David Saintillan

Although the origin of cosmic rays (CRs) remains an open question, collisionless magnetized shock waves are widely regarded as key sites for particle acceleration. Recent theories further suggest that shock-shock collisions in stellar…

Recent observations have shown that coronal shocks driven by coronal mass ejections can develop and accelerate particles within several solar radii in large solar energetic particle (SEP) events. Motivated by this, we present an SEP…

Solar and Stellar Astrophysics · Physics 2017-12-20 Xiangliang Kong , Fan Guo , Joe Giacalone , Hui Li , Yao Chen

It is shown that collisionless shock waves can be driven in unmagnetized electron-positron plasmas by performing a two-dimensional particle-in-cell simulation. At the shock transition region, strong magnetic fields are generated by a…

Astrophysics · Physics 2008-03-31 Tsunehiko N. Kato

Recently a filamentation instability was observed when a laser-generated pair cloud interacted with an ambient plasma. The magnetic field it drove was strong enough to magnetize and accelerate the ambient electrons. It is of interest to…

Plasma Physics · Physics 2018-07-04 M. E. Dieckmann , A. Alejo , G. Sarri , D. Folini , R. Walder

Extreme ultraviolet (EUV) waves are global waves in the solar corona which can accelerate particles. The efficiency of the acceleration depends on local plasma characteristics e.g. Alfv\'en speed and the geometry of the magnetic field. This…

Solar and Stellar Astrophysics · Physics 2026-05-06 C. Cuddy , D. M. Long , M. Nedal , S. Bhunia , P. T. Gallagher

Plasma turbulence is thought to be associated with various physical processes involved in solar flares, including magnetic reconnection, particle acceleration and transport. Using Ramaty High Energy Solar Spectroscopic Imager ({\it RHESSI})…

Solar and Stellar Astrophysics · Physics 2015-05-27 E. P. Kontar , I. G. Hannah , N. H. Bian

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

In this work, it is shown that electrostatic solitons in a plasma with turbulent heating of the electrons through an accelerating electric field can form with very high velocities, reaching up to several order of magnitudes larger than the…

Plasma Physics · Physics 2025-09-03 Mridusmita Das , Murchana Khusroo , Madhurjya P. Bora

It is thought that solar energetic ions associated with coronal/interplanetary shock waves are accelerated to high energies by the diffusive shock acceleration mechanism. For this mechanism to be efficient, intense magnetic turbulence is…

Solar and Stellar Astrophysics · Physics 2023-11-29 A. Afanasiev , R. Vainio , D. Trotta , S. Nyberg , N. Talebpour Sheshvan , H. Hietala , N. Dresing

Thermal electrons cannot directly participate in the process of diffusive acceleration at electron-ion shocks because their Larmor radii are smaller than the shock transition width: this is the well-known electron injection problem of…

High Energy Astrophysical Phenomena · Physics 2022-06-29 Mohamad Shalaby , Rouven Lemmerz , Timon Thomas , Christoph Pfrommer

Collisionless shock waves, ubiquitous in the universe, are crucial for particle acceleration in various astrophysical systems. Currently, the heliosphere is the only natural environment available for their in situ study. In this work, we…

Conventionally, friction is understood as an efficient dissipation mechanism depleting a physical system of energy as an unavoidable feature of any realistic device involving moving parts, e.g., in mechanical brakes. In this work, we…

Accelerator Physics · Physics 2019-05-07 Z. Gong , F. Mackenroth , X. Q. Yan , A. V. Arefiev

When dissipative particles are left alone, their fluctuation energy decays due to collisional interactions, clusters build up and grow with time until the system size is reached. When the effective dissipation is strong enough, this may…

Statistical Mechanics · Physics 2009-10-31 S. Luding , H. J. Herrmann

A new type of proton acceleration stemming from large-scale gradients, low-density targets, irradiated by an intense near-infrared laser is observed. The produced protons are characterized by high-energies (with a broad spectrum), are…