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Diffusive shock acceleration (DSA) of particles at collisionless shocks is the major accepted paradigm about the origin of cosmic rays (CRs). As a theory it was developed during the late 1970s in the so-called test-particle case. If one…

High Energy Astrophysical Phenomena · Physics 2023-10-03 Bojan Arbutina

We present a new code aimed at the simulation of diffusive shock acceleration (DSA), and discuss various test cases which demonstrate its ability to study DSA in its full time-dependent and non-linear developments. We present the numerical…

Astrophysics · Physics 2009-11-13 Gilles Ferrand , Turlough Downes , Alexandre Marcowith

We present results of semi-analytic calculations which show clear evidence for changes in the non-equilibrium ionization behind a supernova remnant forward shock undergoing efficient diffusive shock acceleration (DSA). The efficient…

High Energy Astrophysical Phenomena · Physics 2011-02-11 Daniel J. Patnaude , Donald C. Ellison , Patrick Slane

We provide a both qualitative and quantitative comparison among different approaches aimed to solve the problem of non-linear diffusive acceleration of particles at shocks. In particular, we show that state-of-the-art models (numerical,…

High Energy Astrophysical Phenomena · Physics 2015-03-17 D. Caprioli , Hyesung Kang , A. Vladimirov , T. W. Jones

The intracluster medium (ICM) is expected to experience on average about three passages of weak shocks with low sonic Mach numbers, $M\lesssim 3$, during the formation of galaxy clusters. Both protons and electrons could be accelerated to…

High Energy Astrophysical Phenomena · Physics 2021-06-17 Hyesung Kang

We explore how wave-particle interactions affect diffusive shock acceleration (DSA) at astrophysical shocks by performing time-dependent kinetic simulations, in which phenomenological models for magnetic field amplification (MFA), Alfvenic…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Hyesung Kang

Context. The diffusive shock acceleration mechanism has been widely accepted as the acceleration mechanism for galactic cosmic rays. While self-consistent hybrid simulations have shown how power-law spectra are produced, detailed…

High Energy Astrophysical Phenomena · Physics 2015-06-04 M. Wolff , R. C. Tautz

A well-known paradigm about the origin of Galactic cosmic rays (CRs) is that these high-energy particles are accelerated in the process of diffusive shock acceleration (DSA) at collisionless shocks (at least up to the so-called "knee"energy…

High Energy Astrophysical Phenomena · Physics 2023-04-12 Bojan Arbutina

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

Motivated by cosmic ray (CR) re-acceleration at a potential Galactic Wind Termination Shock (GWTS), we present a numerical model for time-dependent Diffusive Shock Acceleration (DSA). We use the stochastic differential equation solver…

High Energy Astrophysical Phenomena · Physics 2023-12-07 Sophie Aerdker , Lukas Merten , Julia Becker Tjus , Dominik Walter , Frederic Effenberger , Horst Fichtner

The highly amplified magnetic fields suggested by observations of some supernova remnant (SNR) shells are most likely an intrinsic part of efficient particle acceleration by shocks. This strong turbulence, which may result from cosmic ray…

Astrophysics · Physics 2009-11-13 Andrey E. Vladimirov , Andrei M. Bykov , Donald C. Ellison

We report simulations of diffusive particle acceleration in oblique magnetohydrodynamical (MHD) shocks. These calculations are based on extension to oblique shocks of a numerical model for ``thermal leakage'' injection of particles at low…

Astrophysics · Physics 2009-10-28 Hyesung Kang , T. W. Jones

We study the evolution of the energy spectrum of cosmic-ray electrons accelerated at spherically expanding shocks with low Mach numbers and the ensuing spectral signatures imprinted in radio synchrotron emission. Time-dependent simulations…

High Energy Astrophysical Phenomena · Physics 2017-01-18 Hyesung Kang

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

Mildly relativistic, oblique shocks are frequently invoked as possible sites of relativistic particle acceleration and production of strongly variable, polarized multi-wavelength emission from relativistic jet sources such as blazars, via…

High Energy Astrophysical Phenomena · Physics 2019-04-01 Markus Boettcher , Matthew G. Baring

We use kinetic simulations of diffusive shock acceleration (DSA) to study the time-dependent evolution of plane, quasi-parallel, cosmic-ray (CR) modified shocks. Thermal leakage injection of low energy CRs and finite Alfv\'en wave…

High Energy Astrophysical Phenomena · Physics 2011-02-11 Hyesung Kang , Dongsu Ryu , T. W. Jones

In this paper we present an investigation of numerical Monte Carlo simulations of the diffusive shock acceleration in the test particle limit. Very high gamma flow astrophysical plasmas, have been used, from $\gamma_{up}$ $\sim50$ up to…

Astrophysics · Physics 2009-09-25 A. Meli , J. J. Quenby

The spectral index $s$ of particles diffusively accelerated in a relativistic shock depends on the unknown angular diffusion function $\mathcal{D}$, which itself depends on the particle distribution function $f$ if acceleration is…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Yotam Nagar , Uri Keshet

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

We report on a new Monte Carlo method for simulating diffusive shock acceleration (DSA) of solar energetic particles at upstream and downstream regions of quasi-parallel collisionless shock waves under the influence of self-generated…

Space Physics · Physics 2014-08-14 Arto Sandroos , Gang Li , Lulu Zhao