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We present a time-dependent cosmic-ray modified shock model for which the calculated H-alpha emissivity profile agrees well with the H-alpha flux increase ahead of the Balmer-dominated shock at knot g in Tycho's supernova remnant, observed…

Astrophysics · Physics 2014-11-18 A. Y. Wagner , J. -J. Lee , J. C. Raymond , T. W. Hartquist , S. A. E. G. Falle

We present the implementation and the first results of cosmic ray (CR) feedback in the Feedback In Realistic Environments (FIRE) simulations. We investigate CR feedback in non-cosmological simulations of dwarf, sub-$L\star$ starburst, and…

Astrophysics of Galaxies · Physics 2019-09-04 T. K. Chan , D. Keres , P. F. Hopkins , E. Quataert , K. -Y. Su , C. C. Hayward , C. -A. Faucher-Giguere

We develop a formalism for the identification and accurate estimation of the strength of structure formation shocks during cosmological smoothed particle hydrodynamics simulations. Shocks not only play a decisive role for the thermalization…

Astrophysics · Physics 2009-11-11 Christoph Pfrommer , Volker Springel , Torsten A. Ensslin , Martin Jubelgas

Context. Solar energetic particles observed in association with coronal mass ejections (CMEs) are produced by the CME-driven shock waves. The acceleration of particles is considered to be due to diffusive shock acceleration (DSA). Aims. We…

Space Physics · Physics 2016-03-30 Alexandr Afanasiev , Markus Battarbee , Rami Vainio

Context. Observation of Balmer lines from the region around the forward shock of supernova remnants (SNR) may provide valuable information on the shock dynamics and the efficiency of particle acceleration at the shock. Aims. We calculated…

High Energy Astrophysical Phenomena · Physics 2015-06-17 G. Morlino , P. Blasi , R. Bandiera , E. Amato

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

Cosmic rays (CRs) are known to play a key role in many astrophysical environments: they can modify shock dynamics, influence the thermochemistry and the ionization of the interstellar medium, regulate galaxy mass content by driving galactic…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Nimatou-Seydi Diallo , Yohan Dubois , Alexandre Marcowith , Joki Rosdahl , Benoît Commerçon

The tension between recent observations and theories on cosmic ray (CR) diffusion necessitates exploration of new CR diffusion mechanisms. We perform the first numerical study on the mirror diffusion of CRs that is recently proposed by…

High Energy Astrophysical Phenomena · Physics 2023-12-01 Chao Zhang , Siyao Xu

Galaxy clusters grow by gas accretion, mostly from mergers of substructures, which release powerful shock waves into cosmic plasmas and convert a fraction of kinetic energy into thermal energy, amplification of magnetic fields and into the…

High Energy Astrophysical Phenomena · Physics 2019-03-11 A. M. Bykov , F. Vazza , J. A. Kropotina , K. P. Levenfish , F. B. S. Paerels

We use analytic calculations and time-dependent spherically-symmetric simulations to study the properties of isothermal galactic winds driven by cosmic-rays (CRs) streaming at the Alfv\'en velocity. The simulations produce time-dependent…

Astrophysics of Galaxies · Physics 2021-11-24 Eliot Quataert , Yan-Fei Jiang , Todd A. Thompson

We have modeled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parameterizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow…

High Energy Astrophysical Phenomena · Physics 2015-07-15 Donald C. Warren , Donald C. Ellison , Andrei M. Bykov , Shiu-Hang Lee

Cosmic rays (CRs) play a decisive role within our own Galaxy. They provide partial pressure support against gravity, they trace past energetic events such as supernovae, and they reveal the underlying structure of the baryonic matter…

Astrophysics · Physics 2009-11-11 Torsten A. Ensslin , Christoph Pfrommer , Volker Springel , Martin Jubelgas

We study the propagation of mildly-relativistic cosmic rays (CRs) in multiphase interstellar medium environments with conditions typical of nearby disk galaxies. We employ the techniques developed in Armillotta+21 to post-process three…

Astrophysics of Galaxies · Physics 2022-05-04 Lucia Armillotta , Eve C. Ostriker , Yan-Fei Jiang

Cosmic ray (CR) electrons are key tracers of non-thermal processes in galaxies, yet their spectra are often modelled under the untested assumption of steady state between injection and cooling. In this work, we present a time-dependent…

We present a novel implementation of cosmic rays (CR) in the magneto-hydrodynamic code FLASH. CRs are described as separate fluids with different energies. CR advection, energy dependent anisotropic diffusion with respect to the magnetic…

High Energy Astrophysical Phenomena · Physics 2014-06-20 Philipp Girichidis , Thorsten Naab , Stefanie Walch , Michal Hanasz

We suggest a physical mechanism whereby the acceleration time of cosmic rays by shock waves can be significantly reduced. This creates the possibility of particle acceleration beyond the knee energy at ~10^15eV. The acceleration results…

Astrophysics · Physics 2009-11-13 M. A. Malkov , P. H. Diamond

The selfconsistent steady state solution for a strong shock, significantly modified by accelerated particles is obtained on the level of a kinetic description, assuming Bohm-type diffusion. The original problem that is commonly formulated…

Astrophysics · Physics 2009-10-30 M. A. Malkov

Context: Cosmic ray acceleration in galaxy clusters is still an ongoing puzzle, with relativistic electrons forming radio relics at merger shocks and emitting synchrotron radiation. In the present work we perform hybrid-kinetic simulations…

High Energy Astrophysical Phenomena · Physics 2024-02-02 S. S. Boula , J. Niemiec , T. Amano , O. Kobzar

We use 2D and 3D hybrid (kinetic ions - fluid electrons) simulations to investigate particle acceleration and magnetic field amplification at non-relativistic astrophysical shocks. We show that diffusive shock acceleration operates for…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Damiano Caprioli , Anatoly Spitkovsky

The analytical theory of diffusive cosmic ray acceleration at parallel stationary shock waves with magnetostatic turbulence is generalized to arbitrary shock speeds $V_s=\beta_1c$, including in particular relativistic speeds. This is…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Reinhard Schlickeiser
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