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Using test particle simulations we study particle acceleration at highly perpendicular ($\theta_{Bn}\geq 75^\circ$) shocks under conditions of modeling magnetic turbulence. We adopt a backward-in-time method to solve the Newton-Lorentz…

Space Physics · Physics 2017-08-23 F. -J. Kong , G. Qin , L. -H. Zhang

We report the results of 1D particle-in-cell simulations of ultrarelativistic shock waves in proton-electron-positron plasmas. We consider magnetized shock waves, in which the upstream medium carries a large scale magnetic field, directed…

Astrophysics · Physics 2008-11-26 Elena Amato , Jonathan Arons

Diffusive shock acceleration at collisionless shocks is thought to be the source of many of the energetic particles observed in space. Large-scale spatial variations of the magnetic field has been shown to be important in understanding…

High Energy Astrophysical Phenomena · Physics 2015-05-20 F. Guo , J. R. Jokipii , J. Kota

High-energy astrophysical systems frequently contain collisionless relativistic plasmas that are heated by turbulent cascades and cooled by emission of radiation. Understanding the nature of this radiative turbulence is a frontier of…

High Energy Astrophysical Phenomena · Physics 2020-02-05 Vladimir Zhdankin , Dmitri A. Uzdensky , Gregory R. Werner , Mitchell C. Begelman

How thermal particles are accelerated to suprathermal energies is an unsolved issue, crucial for many astrophysical systems. We report novel observations of irregular, dispersive enhancements of the suprathermal particle population upstream…

We present three-dimensional hybrid simulations of collisionless shocks that propagate parallel to the background magnetic field to study the acceleration of protons that forms a high-energy tail on the distribution. We focus on the initial…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Fan Guo , Joe Giacalone

The formation of collisionless shock fronts is an ubiquitous phenomenon in space plasma environments. In the solar wind shocks might accompany coronal mass ejections, while even more violent events, such as supernovae, produce shock fronts…

High Energy Astrophysical Phenomena · Physics 2020-03-17 Cedric Schreiner , Patrick Kilian , Felix Spanier , Patricio A. Muñoz , Jörg Büchner

We consider a stochastic $N$-particle system on a torus in which each particle moving freely can instantaneously thermalize according to the particle configuration at that instant. Following [2], we show that the propagation of chaos does…

Mathematical Physics · Physics 2022-12-22 Paolo Buttà , Mario Pulvirenti

We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting…

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

A new kinetic theory Boltzmann-like collision term including correlations is proposed. In equilibrium it yields the one-particle distribution function in the form of a generalised-Lorentzian resembling but not being identical with the…

Plasma Physics · Physics 2009-10-31 R. A. Treumann

Shock waves propagating in collisionless heliospheric and astrophysical plasmas have been studied extensively over the decades. One prime motivation is to understand the nonthermal particle acceleration at shocks. Although the theory of…

High Energy Astrophysical Phenomena · Physics 2022-09-09 T. Amano , Y. Matsumoto , A. Bohdan , O. Kobzar , S. Matsukiyo , M. Oka , J. Niemiec , M. Pohl , M. Hoshino

We study the diffusion and thermal conductivity of charged particles in the weakly ionized plasma with the power-law q-distributions in nonextensive statistics and without the magnetic field. Electrons and ions have different q-parameters…

Plasma Physics · Physics 2019-03-19 Xiaoxue Ji , Jiulin Du

Velocity distribution functions (VDFs) that exhibit a power-law dependence on the high-energy tail have been the subject of intense research by the plasma physics community. Such functions, known as kappa or superthermal distributions, have…

Plasma Physics · Physics 2016-02-23 Rudi Gaelzer , Luiz Fernando Ziebell

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

Space plasmas in various astrophysical setups can often be both very hot and dilute, making them highly susceptible to waves and fluctuations, which are generally self-generated and maintained by kinetic instabilities. In this sense, we…

We study the collision frequencies of particles in the weakly and highly ionized plasmas with the power-law q-distributions in nonextensive statistics. We derive the average collision frequencies of neutral-neutral particle,…

Plasma Physics · Physics 2021-01-08 Yue Wang , Jiulin Du

We study the nonextensive parameter for the rotating astrophysical systems with power-law distributions, including both the rotating self-gravitating system and the rotating space plasma. We extend the equation of nonextensive parameter to…

Statistical Mechanics · Physics 2017-02-10 Haining Yu , Jiulin Du

In situ measurements of kinetic scale current sheets in the solar wind show that they are often approximately force-free although the plasma beta is of order one. They frequently display systematic asymmetric and anti-correlated spatial…

Solar and Stellar Astrophysics · Physics 2025-09-30 Sophie Boswell , Thomas Neukirch , Anton Artemyev , Ivan Vasko , Oliver Allanson

The measurement of electron temperatures and metallicities in H ii regions and Planetary Nebulae (PNe) has-for several decades-presented a problem: results obtained using different techniques disagree. What it worse, they disagree…

Astrophysics of Galaxies · Physics 2012-06-20 David C. Nicholls , Michael A. Dopita , Ralph S. Sutherland

Density and temperature conditions in many stellar core (like the solar core) imply the presence of nonideal plasma effects with memory and long-range interactions between particles. This aspect suggests the possibility that the stellar…

Nuclear Theory · Physics 2017-08-23 A. Lavagno , P. Quarati