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We explore electron pre-acceleration at high Mach-number nonrelativistic perpendicular shocks at, e.g., young supernova remnants, which are a prerequisite of further acceleration to very high energies via diffusive shock acceleration. Using…

High Energy Astrophysical Phenomena · Physics 2019-11-06 Artem Bohdan , Jacek Niemiec , Martin Pohl , Yosuke Matsumoto , Takanobu Amano , Masahiro Hoshino

In this work, we investigate collisionless shocks propagating in a relativistically hot unmagnetized electron-positron plasmas. We estimate the dissipation fraction at shocks in the relativistically hot plasma, showing that it is…

High Energy Astrophysical Phenomena · Physics 2024-10-21 Kamiido Kazuki , Ohira Yutaka

Shock accelerated electrons are found in many astrophysical environments, and the mechanisms by which they are accelerated to high energies are still not completely clear. For relatively high Mach numbers, the shock is supercritical, and…

Space Physics · Physics 2018-10-17 D. Trotta , D. Burgess

For parameters that are applicable to the conditions at young supernova remnants, we present results of 2D3V particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at 45-deg…

High Energy Astrophysical Phenomena · Physics 2016-03-23 Volkmar Wieland , Martin Pohl , Jacek Niemiec , Iman Rafighi , Ken-Ichi Nishikawa

Electron accelerations at high Mach number collision-less shocks are investigated by means of two-dimensional electromagnetic Particle-in-Cell simulations with various Alfven Mach numbers, ion-to-electron mass ratios, and the upstream…

High Energy Astrophysical Phenomena · Physics 2013-11-01 Yosuke Matsumoto , Takanobu Amano , Masahiro Hoshino

We report on the first steady-state simulations of strong plasma shocks with fully kinetic ions and electrons, independently confirmed by two fully kinetic codes (an Eulerian continuum and a Lagrangian particle-in-cell). While kinetic…

Collisionless shocks are common features in space and astrophysical systems where supersonic plasma flows interact, such as in the solar wind, the heliopause, and supernova remnants. Recent experimental capabilities and diagnostics allow…

This study investigates the applicability of the semi-implicit particle-in-cell code FLEKS to heliospheric shock simulations. We examine one- and two-dimensional local planar shock simulations, initialized using MHD states with upstream…

Space Physics · Physics 2025-10-31 Hongyang Zhou , Yuxi Chen , Chuanfei Dong , Liang Wang , Ying Zou , Brian Walsh , Gábor Tóth

Magnetized collisionless shocks drive particle acceleration broadly in space and astrophysics. We perform the first large-scale particle-in-cell simulations with realistic laboratory parameters (density, temperature, and velocity) to…

Plasma Physics · Physics 2024-05-24 P. Liu , D. Wu , D. W. Yuan , G. Zhao , Z. M. Sheng , X. T. He , J. Zhang

The localized deposition of the energy of a laser pulse, as it ablates a solid target, introduces high thermal pressure gradients in the plasma. The thermal expansion of this laser-heated plasma into the ambient medium (ionized residual…

Plasma Physics · Physics 2009-11-30 M E Dieckmann , G Sarri , L Romagnani , I Kourakis , M Borghesi

We investigate the acceleration of light particles in perpendicular shocks for plasmas consisting of a mixture of leptonic and hadronic particles. Starting from the full set of conservation equations for the mixed plasma constituents, we…

High Energy Astrophysical Phenomena · Physics 2015-06-05 A. Stockem , F. Fiuza , R. A. Fonseca , L. O. Silva

Ab-initio numerical study of collisionless shocks in electron-ion unmagnetized plasmas is performed with fully relativistic particle in cell simulations. The main properties of the shock are shown, focusing on the implications for particle…

High Energy Astrophysical Phenomena · Physics 2011-02-11 S. F. Martins , R. A. Fonseca , L. O. Silva , W. B. Mori

Plasma instabilities (e.g., Buneman, Weibel and other two-stream instabilities) excited in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a new 3-D relativistic particle-in-cell code, we…

High Energy Astrophysical Phenomena · Physics 2011-02-11 K. -I. Nishikawa , J. Niemiec , P. E. Hardee , M. Medvedev , H. Sol , Y. Mizuno , B. Zhang , M. Pohl , M. Oka , D. H. Hartmann

Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms…

Plasma Physics · Physics 2015-07-23 T. Liseykina , G. Dudnikova , V. Vshivkov , M. Malkov

The course of non-thermal electron ejection in relativistic unmagnetized electron-ion shocks is investigated by performing self-consistent particle-in-cell simulations. The shocks are excited through the injection of relativistic jet into…

High Energy Astrophysical Phenomena · Physics 2016-08-24 Kazem Ardaneh , Dongsheng Cai , Ken-Ichi Nishikawa

We study a relativistic collisionless electron-positron shock propagating into an unmagnetized ambient medium using 2D particle-in-cell simulations of unprecedented duration and size. The shock generates intermittent magnetic structures of…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Daniel Groselj , Lorenzo Sironi , Anatoly Spitkovsky

In this paper, we study shock structures of collisionless shocks in partially ionized plasmas by means of two-dimensional hybrid simulations, where the shock is a perpendicular shock with shock velocity Vsh ~ 40 Va ~ 1333 km/s and the…

High Energy Astrophysical Phenomena · Physics 2016-02-03 Yutaka Ohira

We present results of 2D3V particle-in-cell simulations of non-relativistic plasma collisions with absent or parallel large-scale magnetic field for parameters applicable to the conditions at young supernova remnants. We study the collision…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Jacek Niemiec , Martin Pohl , Antoine Bret , Volkmar Wieland

Collisionless shocks occur in various fields of physics. In the context of space and astrophysics they have been investigated for many decades. However, a thorough understanding of shock formation and particle acceleration is still missing.…

Plasma Physics · Physics 2015-09-18 A. Stockem Novo , A. Bret , R. A. Fonseca , L. O. Silva

Particle acceleration in collisionless plasma systems is a central question in astroplasma and astroparticle physics. The structure of the acceleration regions, electron-ion energy equilibration, preacceleration of particles at shocks to…

High Energy Astrophysical Phenomena · Physics 2020-02-19 Martin Pohl , Masahiro Hoshino , Jacek Niemiec