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The theoretical prediction that magnetic reconnection spontaneously drives turbulence has been supported by magnetohydrodynamic (MHD) and kinetic simulations. While reconnection with externally driven turbulence is accepted as an effective…

Plasma Physics · Physics 2023-08-16 Jian-Fu Zhang , Siyao Xu , Alex Lazarian , Grzegorz Kowal

Non-thermal emission has been detected in WR-stars for many years at long wavelengths spectral range, in general attributed to synchrotron emission. Two key ingredients are needed to explain such emissions, namely magnetic fields and…

High Energy Astrophysical Phenomena · Physics 2015-10-22 D. Falceta-Goncalves

Relativistic reconnection has been invoked as a mechanism for particle acceleration in numerous astrophysical systems. According to idealised analytical models reconnection produces a bulk relativistic outflow emerging from the reconnection…

High Energy Astrophysical Phenomena · Physics 2016-08-17 Daniel Kagan , Ehud Nakar , Tsvi Piran

We propose that non-thermal electrons are efficiently accelerated by first-order Fermi process at the fast shock, as a natural consequence of the new magnetohydrodynamic picture of the flaring region revealed with Yohkoh. An oblique fast…

Astrophysics · Physics 2009-10-30 Saku Tsuneta , Tsuguya Naito

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

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

Shocks in astrophysical fluids can generate suprathermal particles by first order (or diffusive) Fermi acceleration. In the test particle regime there is a simple relation between the spectrum of the accelerated particles and the jump…

Astrophysics · Physics 2009-11-06 Pasquale Blasi

Radio observations at low frequencies with the Low Frequency Array (LOFAR) start discovering gigantic radio bridges connecting pairs of massive galaxy clusters. These observations probe unexplored mechanisms of in situ particle acceleration…

High Energy Astrophysical Phenomena · Physics 2020-02-19 G. Brunetti , F. Vazza

In recent years, there has been considerable interest in understanding the motion in Hamiltonian systems when phase space is divided into stochastic and integrable regions. This paper studies one aspect of this problem, namely, the motion…

Chaotic Dynamics · Physics 2007-05-23 Charles F. F. Karney

Power-law distributions are a near universal feature of energetic particle spectra in the heliosphere. Anomalous Cosmic Rays (ACRs), super-Alfv\'enic ions in the solar wind and the hardest energetic electron spectra in flares all have…

Solar and Stellar Astrophysics · Physics 2015-06-11 J. F. Drake , M. Swisdak , R. L. Fermo

Collisionless magnetic reconnection is a prime candidate to account for flare-like or steady emission, outflow launching, or plasma heating, in a variety of high-energy astrophysical objects, including ones with relativistic ion-electron…

High Energy Astrophysical Phenomena · Physics 2014-11-05 Mickaël Melzani , Rolf Walder , Doris Folini , Christophe Winisdoerffer , Jean M. Favre

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

Context: The strong electric fields associated with magnetic reconnection in solar flares are a plausible mechanism to accelerate populations of high energy, non-thermal particles. One such reconnection scenario occurs at a 3D magnetic null…

Solar and Stellar Astrophysics · Physics 2015-06-03 Adam J. Stanier , Philippa K. Browning , Silvia Dalla

Magnetic reconnection in the partially ionized solar chromosphere is studied in 2.5-dimensional magnetohydrodynamic simulations including radiative cooling and ambipolar diffusion. A Harris current sheet with and without a guide field is…

Solar and Stellar Astrophysics · Physics 2015-09-24 Lei Ni , Bernhard Kliem , Jun Lin , Ning Wu

The ubiquitous turbulence in astrophysical plasmas is important for both magnetic reconnection and reconnection acceleration. We study the particle acceleration during fast 3D turbulent reconnection with reconnection-driven turbulence.…

Plasma Physics · Physics 2023-01-11 Siyao Xu , Alex Lazarian

We demonstrate that particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. Some examples of such flows include spontaneous turbulent reconnection and decaying magnetohydrodynamic (MHD)…

High Energy Astrophysical Phenomena · Physics 2016-03-04 Andrey Beresnyak , Hui Li

Magnetic reconnection in strongly magnetized astrophysical plasma environments is believed to be the primary process for fast energy release and particle energization. Currently there is strong interest in relativistic magnetic…

High Energy Astrophysical Phenomena · Physics 2020-08-26 Fan Guo , Yi-Hsin Liu , Xiaocan Li , Hui Li , William Daughton , Patrick Kilian

The acceleration of energetic particles in astrophysical shear flows is analyzed. We show that in the presence of a non-relativistic gradual velocity shear, power law particle momentum distributions $f(p) \propto p^{-(3+\alpha)}$ may be…

Astrophysics · Physics 2009-11-10 F. M. Rieger , P. Duffy

Electron acceleration to non-thermal energies in low Mach number (M<5) shocks is revealed by radio and X-ray observations of galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Diffusive…

High Energy Astrophysical Phenomena · Physics 2014-10-14 Xinyi Guo , Lorenzo Sironi , Ramesh Narayan

The role of MHD turbulence in the cosmic ray acceleration process in a volume with a reconnecting magnetic field is studied by means of Monte Carlo simulations. We performed modelling of proton acceleration with the 3D analytic model of…

Astrophysics · Physics 2009-10-31 Tomasz Kobak , Michal Ostrowski