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Galactic cosmic rays (CR) are particles presumably accelerated in supernova remnant shocks that propagate in the interstellar medium up to the densest parts of molecular clouds, losing energy and their ionisation efficiency because of the…

High Energy Astrophysical Phenomena · Physics 2016-05-25 M. Padovani , A. Marcowith , P. Hennebelle , K. Ferrière

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 a hydrodynamical simulation of the turbulent, magnetized, supernova (SN)-driven interstellar medium (ISM) in a stratified box that dynamically couples the injection and evolution of cosmic rays (CRs) and a self-consistent…

We review some recent findings on diffusion of cosmic rays (CRs) in magnetohydrodynamic (MHD) turbulence obtained by adopting the numerically-tested model of MHD turbulence, including perpendicular superdiffusion of CRs, inefficient…

High Energy Astrophysical Phenomena · Physics 2021-10-19 Siyao Xu

Within a test-particle description of the acceleration process in parallel nonrelativistic shocks, we present an analytic treatment of the electron injection. We estimate the velocity distribution of the injected electrons as the product of…

Astrophysics · Physics 2007-05-23 O. Petruk , R. Bandiera

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

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

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

Cosmic-ray acceleration at non-relativistic shocks relies on scattering by turbulence that the cosmic rays drive upstream of the shock. We explore the rate of energy transfer from cosmic rays to non-resonant Bell modes and the spectral…

High Energy Astrophysical Phenomena · Physics 2021-11-17 Martin Pohl

We investigate the dynamical interaction between cosmic rays (CRs) and the multiphase interstellar medium (ISM) using numerical magnetohydrodynamic (MHD) simulations with a two-moment CR solver and TIGRESS simulations of star-forming…

Astrophysics of Galaxies · Physics 2024-01-10 Lucia Armillotta , Eve C. Ostriker , Chang-Goo Kim , Yan-Fei Jiang

Using three-dimensional magnetohydrodynamics simulations, we show that the efficiency of cosmic-ray (CR) production at supernova remnants (SNRs) is over-predicted if it could be estimated based on proper motion measurements of H$\alpha$…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jiro Shimoda , Tsuyoshi Inoue , Yutaka Ohira , Ryo Yamazaki , Aya Bamba , Jacco Vink

A novel collisionless shock jump condition is suggested by modeling the entropy production at the shock transition region. We also calculate downstream developments of the atomic ionization balance and the ion temperature relaxation in…

High Energy Astrophysical Phenomena · Physics 2022-07-27 Jiro Shimoda , Yutaka Ohira , Aya Bamba , Yukikatsu Terada , Ryo Yamazaki , Tsuyoshi Inoue , Shuta J. Tanaka

We study penetration of interstellar cosmic rays (CRs) into molecular clouds surrounded by nonuniform diffuse envelopes. The present work generalizes our earlier model of CR self-modulation (Ivlev et al. 2018, Dogiel et al. 2018), in which…

High Energy Astrophysical Phenomena · Physics 2024-07-08 D. O. Chernyshov , A. V. Ivlev , A. M. Kiselev

More and more observations have indicated the existence of slow diffusion phenomena in astrophysical environments, such as around the supernova remnants and pulsar $\gamma$-ray halos, where the diffusion coefficient of cosmic rays (CRs)…

High Energy Astrophysical Phenomena · Physics 2025-06-24 Yawen Xiao , Jianfu Zhang , Siyao Xu

When the pressure of particles accelerated at shock waves is no longer negligible compared to the kinetic pressure of the gas, the linear theory of diffusive shock acceleration breaks down. This is expected in particular when the shock…

High Energy Astrophysical Phenomena · Physics 2021-12-22 Thibault Vieu , Stefano Gabici , Vincent Tatischeff

In the present paper we discuss the modifications introduced into the first-order Fermi shock acceleration process due to a finite extent of diffusive regions near the shock or due to boundary conditions leading to an increased particle…

Astrophysics · Physics 2009-10-28 M. Ostrowski , R. Schlickeiser

The properties of cosmic shock waves are studied through numerical simulations in two cosmological scenarios (SCDM and LCDM). The scaling relations for the average radius and velocity associated with the accretion shocks are somewhat…

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

Cosmic-ray (CR) feedback is widely recognized as a key regulator of galaxy formation. After being accelerated at supernova remnant shocks, CRs propagate through the interstellar medium (ISM), establishing smooth large-scale distributions…

Astrophysics of Galaxies · Physics 2025-10-21 Timon Thomas , Christoph Pfrommer , Rüdiger Pakmor , Rouven Lemmerz , Mohamad Shalaby

We present new results characterizing cosmological shocks within adaptive mesh refinement N-Body/hydrodynamic simulations that are used to predict non-thermal components of large-scale structure. This represents the first study of shocks…

Despite being studied for many years, the structure of collisionless shocks is still not fully determined. Such shocks are known to be accelerators of cosmic rays, which, in turn, modify the shock structure. The shock width $\lambda$ is…

High Energy Astrophysical Phenomena · Physics 2024-05-15 Antoine Bret , Asaf Pe'er