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Magnetic reconnection occurs ubiquitously in the universe and is often invoked to explain fast energy release and particle acceleration in high-energy astrophysics. The study of relativistic magnetic reconnection in the magnetically…

High Energy Astrophysical Phenomena · Physics 2024-04-23 Fan Guo , Yi-Hsin Liu , Seiji Zenitani , Masahiro Hoshino

Solar flares are explosive events in the solar corona, representing fast conversion of magnetic energy into thermal and kinetic energy, and hence radiation, due to magnetic reconnection. Modelling is essential for understanding and…

Solar and Stellar Astrophysics · Physics 2019-02-13 M. Gordovskyy , P. K. Browning , R. F. Pinto

Spatially-resolved X-ray observations are the key to understanding electron acceleration in solar flares. Currently, the underlying processes that efficiently energize solar flare particles are poorly constrained. Abundant flare…

Solar and Stellar Astrophysics · Physics 2026-03-09 Morgan Stores , Natasha Jeffrey , Ewan Dickson , James McLaughlin , Eduard Kontar

We present a new algorithm for the identification and physical characterization of current sheets and reconnection sites in 2D and 3D large scale relativisticmagnetohydrodynamic numerical simulations. This has been implemented in the PLUTO…

High Energy Astrophysical Phenomena · Physics 2023-05-29 Matteo Nurisso , Annalisa Celotti , Andrea Mignone , Gianluigi Bodo

In this introductory chapter, we provide a brief summary of the successes and remaining challenges in understanding the solar flare phenomenon and its attendant implications for particle acceleration mechanisms in astrophysical plasmas. We…

Solar and Stellar Astrophysics · Physics 2011-09-28 Brian R. Dennis , A. Gordon Emslie , Hugh S. Hudson

We investigate magnetic reconnection in systems simultaneously containing asymmetric (anti-parallel) magnetic fields, asymmetric plasma densities and temperatures, and arbitrary in-plane bulk flow of plasma in the upstream regions. Such…

Plasma Physics · Physics 2016-08-24 C. E. Doss , P. A. Cassak , M. Swisdak

A major open issue concerning the active Sun is the effectiveness with which magnetic reconnection accelerates electrons in flares. A paper published by {\em{Nature}} in 2022 used microwave observations to conclude that the Sun is an almost…

Solar and Stellar Astrophysics · Physics 2025-02-10 Anna Volpara , Paolo Massa , Michele Piana , Anna Maria Massone , A Gordon Emslie

Electron and proton acceleration in three-dimensional electric and magnetic fields is studied through test particle simulations. The fields are obtained by a three-dimensional magnetohydrodynamic simulation of magnetic reconnection in slab…

Astrophysics · Physics 2008-11-26 Marco Onofri , Heinz Isliker , Loukas Vlahos

The acceleration of charged particles is relevant to the solar corona over a broad range of scales and energies. High-energy particles are usually detected in concomitance with large energy release events like solar eruptions and flares,…

Solar and Stellar Astrophysics · Physics 2014-02-27 S. Dalena , A. F. Rappazzo , P. Dmitruk , A. Greco , W. H. Matthaeus

Magnetic field-aligned electric fields are characteristic features of magnetic reconnection processes operating in externally agitated magnetized plasmas. An especially interesting environment for such a process are the coronae of accretion…

Astrophysics · Physics 2011-05-23 R. Schopper , H. Lesch , G. T. Birk

Particle acceleration in solar flares remains an outstanding problem in solar physics. It is yet unclear which of the acceleration mechanisms dominates and how exactly is the excessive magnetic energy transferred to the nonthermal and other…

Solar and Stellar Astrophysics · Physics 2019-09-25 Alexander T. Altyntsev , Nataliia S. Meshalkina , Alexandra L. Lysenko , Gregory D. Fleishman

We study linear and nonlinear development of relativistic and ultrarelativistic current sheets of pair plasmas with antiparallel magnetic fields. Two types of two-dimensional problems are investigated by particle-in-cell simulations. First,…

Astrophysics · Physics 2011-11-10 S. Zenitani , M. Hoshino

The aim of this work is to investigate and characterise particle behaviour in a 3D magnetohydrodynamic (MHD) model of a reconnecting magnetic separator. We use a relativistic guiding-centre test-particle code to investigate electron and…

Solar and Stellar Astrophysics · Physics 2015-12-23 J. Threlfall , J. E. H. Stevenson , C. E. Parnell , T. Neukirch

RHESSI measurements relevant to the fundamental processes of energy release and particle acceleration in flares are summarized. RHESSI's precise measurements of hard X-ray continuum spectra enable model-independent deconvolution to obtain…

Solar and Stellar Astrophysics · Physics 2011-10-11 R. P. Lin

Magnetic reconnection is invoked as one of the primary mechanisms to produce energetic particles. We employ large-scale three-dimensional (3D) particle-in-cell simulations of reconnection in magnetically-dominated ($\sigma=10$) pair plasmas…

High Energy Astrophysical Phenomena · Physics 2021-12-15 Hao Zhang , Lorenzo Sironi , Dimitrios Giannios

The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need…

Solar and Stellar Astrophysics · Physics 2014-11-20 R. T. James McAteer , Peter T. Gallagher , Paul A. Conlon

Magnetic reconnection is a fundamental physical process converting magnetic energy into not only plasma energy but also particle energy in various astrophysical phenomena. In this letter, we show a unique dataset of a solar flare where…

Solar and Stellar Astrophysics · Physics 2022-01-12 Lei Lu , Li Feng , Alexander Warmuth , Astrid M. Veronig , Jing Huang , Siming Liu , Weiqun Gan , Zongjun Ning , Beili Ying , Guannan Gao

Astrophysical observations suggest that magnetic reconnection in relativistic plasmas plays an important role in the acceleration of energetic particles. Modeling this accurately requires numerical schemes capable of addressing large scales…

Plasma Physics · Physics 2025-09-16 K. M. Schoeffler , F. Bacchini , K. Kormann , B. Eichmann , M. E. Innocenti

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

The aim of this work is to investigate and characterise particle behaviour in an (observationally-driven) 3D MHD model of the solar atmosphere above a slowly evolving, non-flaring active region. We use a relativistic guiding-centre particle…

Solar and Stellar Astrophysics · Physics 2016-02-17 J. Threlfall , Ph. -A. Bourdin , T. Neukirch , C. E. Parnell