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Finding the injection threshold for diffusive shock acceleration (DSA) of electrons in collisionless shocks has been a longstanding unsolved problem. Using first-principles kinetic simulations, we identify the conditions for electron…

High Energy Astrophysical Phenomena · Physics 2025-06-12 Siddhartha Gupta , Damiano Caprioli , Anatoly Spitkovsky

Particle acceleration in relativistic shocks is studied analytically in the test-particle, small-angle scattering limit, for an arbitrary velocity-angle diffusion function D. Accurate analytic expressions for the spectral index s are…

Astrophysics · Physics 2008-11-26 Uri Keshet

The shock waves produce relativistic particles via the diffusive shock acceleration (DSA) mechanism. Among various circumstances, fast acceleration has been expected for perpendicular shocks. We investigate the acceleration time and the…

High Energy Astrophysical Phenomena · Physics 2020-07-15 Shoma F. Kamijima , Yutaka Ohira , Ryo Yamazaki

The effect of particles that undergo strong diffusive-shock-acceleration on the stability of the accelerating shock is investigated. A two-fluid model is employed in which the accelerated particles are treated as a fluid whose effect is…

Astrophysics · Physics 2007-05-23 M. Mond , L. O'C. Drury

The radio spectra of many shell-type supernova remnants show deviations from those expected on theoretical grounds. In this paper we determine the effect of stochastic reacceleration on the spectra of electrons in the GeV band and at lower…

High Energy Astrophysical Phenomena · Physics 2015-01-28 M. Pohl , A. Wilhelm , I. Telezhinsky

The recent discoveries in the theory of diffusive shock acceleration (DSA) that stem from first-principle kinetic plasma simulations are discussed. When ion acceleration is efficient, the back-reaction of non-thermal particles and…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Damiano Caprioli , Colby Haggerty , Pasquale Blasi

Spectroscopic observations of the 2006 outburst of the recurrent nova RS Ophiuchi at both infrared (IR) and X-ray wavelengths have shown that the blast wave has decelerated at a higher rate than predicted by the standard test-particle…

Astrophysics · Physics 2009-11-13 V. Tatischeff , M. Hernanz

Recent studies about collisionless shocks in partially ionized plasmas showed that some of neutral particles leak into the shock upstream region from the downstream region. In this paper, we perform a linear analysis and show that acoustic…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Yutaka Ohira

Context: Multiwavelength observations of supernova remnants can be explained within the framework of the diffusive shock acceleration theory, which allows effective conversion of the explosion energy into cosmic rays. Although the models of…

Astrophysics · Physics 2009-11-13 L. O'C. Drury , F. A. Aharonian , D. Malyshev , S. Gabici

Ion-neutral collisions may lead to the damping of Alfven waves in chromospheric and prominence plasmas. Neutral helium atoms enhance the damping in certain temperature interval, where the ratio of neutral helium and neutral hydrogen atoms…

Solar and Stellar Astrophysics · Physics 2015-06-12 T. V. Zaqarashvili , M. L. Khodachenko , R. Soler

Diffusive shock acceleration is the theory of particle acceleration through multiple shock crossings. In order for this process to proceed at a rate that can be reconciled with observations of high-energy electrons in the vicinity of the…

High Energy Astrophysical Phenomena · Physics 2015-06-04 K. M. Schure , A. R. Bell , L. O'C Drury , A. M. Bykov

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

The paper is concerned with the propagation of ion-acoustic shock waves in a collision dominated plasma. We firstly establish the existence and uniqueness of a small-amplitude smooth travelling wave, then justify its approximation to the…

Analysis of PDEs · Mathematics 2018-06-25 Renjun Duan , Shuangqian Liu , Zhu Zhang

We use large hybrid simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient, we find…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Damiano Caprioli , Anatoly Spitkovsky

We use large hybrid (kinetic protons-fluid electrons) simulations to investigate the transport of energetic particles in self-consistent electromagnetic configurations of collisionless shocks. In previous papers of this series, we showed…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Damiano Caprioli , Anatoly Spitkovsky

Motivated by recent unsuccessful efforts to detect the predicted flux of TeV gamma-rays from supernova remnants, we present a critical examination of the theory on which these predictions are based. Three crucial problems are identified:…

Astrophysics · Physics 2008-11-26 J. G. Kirk , R. O. Dendy

Electron acceleration in collisionless shocks with arbitrary magnetic field orientations is discussed. It is shown that the injection of thermal electrons into diffusive shock acceleration process is achieved by an electron beam with a…

High Energy Astrophysical Phenomena · Physics 2010-05-25 Takanobu Amano , Masahiro Hoshino

Estimating the cosmic-ray acceleration efficiency $ \epsilon $ in supernova remnants (SNRs) through observations is a challenging task in general. Based on the Rankine-Hugoniot shock conditions, we find an anticorrelation between $ \epsilon…

High Energy Astrophysical Phenomena · Physics 2018-12-21 Yiran Zhang , Siming Liu

A numerical study on ion acceleration in electrostatic shock waves is presented, with the aim of determining the best plasma configuration to achieve quasi-monoenergetic ion beams in laser-driven systems. It was recently shown that tailored…

Plasma Physics · Physics 2018-03-14 E. Boella , F. Fiúza , A. Stockem Novo , R. Fonseca , L. O. Silva

Recent observations of non-thermal X-rays from supernova remnants have been attributed to synchrotron radiation from the loss-steepened tail of a non-thermal distribution of electrons accelerated at the remnant blast wave. In diffusive…

Astrophysics · Physics 2009-11-10 S. P. Reynolds