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Cosmic rays are transported out of the galaxy by diffusion and advection due to streaming along magnetic field lines and resonant scattering off self-excited MHD waves. Thus momentum is transferred to the plasma via the frozen-in waves as a…

High Energy Astrophysical Phenomena · Physics 2013-04-05 E. A. Dorfi , D. Breitschwerdt

We conduct global galactic--scale magnetohydrodynamical (MHD) simulations of the cosmic--ray driven dynamo. We assume that exploding stars deposit small--scale, randomly oriented, dipolar magnetic fields into the differentially rotating…

Astrophysics of Galaxies · Physics 2009-11-13 Michał Hanasz , Dominik Wóltański , Kacper Kowalik , Rafał Pawłaszek

We investigate stochastic particle acceleration in accretion flows. It is believed that the magnetorotational instability (MRI) generates turbulence inside accretion flows and that cosmic rays (CRs) are accelerated by the turbulence. We…

High Energy Astrophysical Phenomena · Physics 2016-05-25 Shigeo S. Kimura , Kenji Toma , Takeru K. Suzuki , Shu-ichiro Inutsuka

We investigate the dynamical importance of a newly recognized possible source of significant feedback generated during structure formation; namely cosmic ray (CR) pressure. We present evidence for the existence of numerous shocks in the hot…

Astrophysics · Physics 2007-05-23 Francesco Miniati , Dongsu Ryu , T. W. Jones , Hyesung Kang

Collisionless shocks with low sonic Mach numbers, $M_{\rm s} \lesssim 4$, are expected to accelerate cosmic ray (CR) protons via diffusive shock acceleration (DSA) in the intracluster medium (ICM). However, observational evidence for CR…

High Energy Astrophysical Phenomena · Physics 2018-10-10 Ji-Hoon Ha , Dongsu Ryu , Hyesung Kang , Allard Jan van Marle

We study the acceleration of cosmic rays by collisionless structure formation shocks with ENZO grid simulations. Data from the FERMI satellite enable the use of galaxy clusters as a testbed for particle acceleration models. Based on…

Astrophysics of Galaxies · Physics 2016-03-23 F. Vazza , M. Brueggen , D. Wittor , C. Gheller , D. Eckert , M. Stubbe

There is an emerging consensus that large amounts of gas do not shock heat in the circumgalactic medium (CGM) of massive galaxies, but instead pierce deep into haloes from the cosmic web via filaments. To better resolve this process…

Astrophysics of Galaxies · Physics 2020-09-25 Jake S. Bennett , Debora Sijacki

We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae…

Astrophysics of Galaxies · Physics 2022-12-28 Christine M. Simpson , Rüdiger Pakmor , Christoph Pfrommer , Simon C. O. Glover , Rowan Smith

We present a numerical algorithm for the incorporation of the active cosmic ray transport, into the ZEUS-3D magnetohydrodynamical code. The cosmic ray transport is described by the diffusion-advection equation. The applied form of the…

Astrophysics · Physics 2009-11-10 M. Hanasz , H. Lesch

Galactic cosmic rays (CRs) play a crucial role in galaxy formation and evolution by altering gas dynamics and chemistry across multiple scales. Typical numerical simulations of CR transport assume a constant diffusion coefficient for the…

Astrophysics of Galaxies · Physics 2025-10-16 Sarah Thiele , Romain Teyssier

We investigate whether stochastic acceleration associated with pressure-anisotropy-driven magnetogenesis can generate a dynamically significant population of cosmic rays (CRs) prior to nonlinear structure formation. As magnetic fields…

High Energy Astrophysical Phenomena · Physics 2026-05-26 Ji-Hoon Ha

We present a nonlinear Monte Carlo model of efficient diffusive shock acceleration (DSA) where the magnetic turbulence responsible for particle diffusion is calculated self-consistently from the resonant cosmic-ray (CR) streaming…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Andrei M. Bykov , Donald C. Ellison , Sergei M. Osipov , Andrey E. Vladimirov

We present the latest improvements in the Center for Radiative Shock Hydrodynamics (CRASH) code, a parallel block-adaptive-mesh Eulerian code for simulating high-energy-density plasmas. The implementation can solve for radiation models with…

Solar and Stellar Astrophysics · Physics 2012-06-08 B. van der Holst , G. Toth , I. V. Sokolov , B. R. Torralva , K. G. Powell , R. P. Drake

We study diffusion of Cosmic Rays (CRs) in turbulent magnetic fields using test particle simulations. Electromagnetic fields are produced in direct numerical MHD simulations of turbulence and used as an input for particle tracing, particle…

Astrophysics of Galaxies · Physics 2015-05-18 A. Beresnyak , H. Yan , A. Lazarian

We review the present status of the cosmic ray acceleration theory in mildly relativistic shock waves. Due to the involved substantial particle anisotropies analytical methods can tackle only simple situations involving weakly turbulent…

Astrophysics · Physics 2007-05-23 M. Ostrowski

We have developed a novel computer code designed to follow the evolution of cosmic-ray modified shocks, including the full momentum dependence of the particles for a realistic diffusion coefficient model. In this form the problem is…

Astrophysics · Physics 2009-10-31 Hyesung Kang , T. W. Jones , R. J. LeVeque , K. M. Shyue

Recently, Zhang & Liu (2024) proposed a turbulent convection model for multiscale anisotropies of cosmic rays (CRs), with an assumption of isotropic diffusion such that the anisotropies are statistically isotropic. However, this assumption…

High Energy Astrophysical Phenomena · Physics 2025-06-26 Yiran Zhang , Siming Liu

Observations show that the magnetic field in young supernova remnants (SNRs) is significantly stronger than can be expected from the compression of the circumstellar medium (CSM) by a factor of four expected for strong blast waves.…

Astrophysics of Galaxies · Physics 2009-08-05 K. M. Schure , J. Vink , A. Achterberg , R. Keppens

The transport of cosmic rays (CRs) is crucial for the understanding of almost all high-energy phenomena. Both pre-existing large-scale magnetohydrodynamic (MHD) turbulence and locally generated turbulence through plasma instabilities are…

High Energy Astrophysical Phenomena · Physics 2018-02-28 Olga Lebiga , Reinaldo Santos-Lima , Huirong Yan

Anisotropic diffusion is imperative in understanding cosmic ray diffusion across the Galaxy, the heliosphere, and the interplay of cosmic rays with the Galactic magnetic field. This diffusion term contributes to the highly stiff nature of…

High Energy Astrophysical Phenomena · Physics 2023-08-09 Pranab J. Deka , Ralf Kissmann , Lukas Einkemmer