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In the Milky Way, cosmic rays (CRs) are dynamically important in the interstellar medium, contribute to hydrostatic balance, and may help regulate star formation. However, we know far less about the importance of CRs in galaxies whose gas…

Astrophysics of Galaxies · Physics 2021-01-27 Roland M. Crocker , Mark R. Krumholz , Todd A. Thompson

A cosmological hydrodynamic code is described, which includes a routine to compute cosmic ray acceleration and transport in a simplified way. The routine was designed to follow explicitly diffusive acceleration at shocks, and second-order…

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

Understanding the physical mechanisms that control galaxy formation is a fundamental challenge in contemporary astrophysics. Recent advances in the field of astrophysical feedback strongly suggest that cosmic rays (CRs) may be crucially…

High Energy Astrophysical Phenomena · Physics 2023-10-10 Mateusz Ruszkowski , Christoph Pfrommer

Cosmic ray (CR) feedback in galaxy evolution has seen a theoretical resurgence in the past decade, but significant uncertainties remain in CR transport through the interstellar and circum-galactic media (ISM and CGM). While several works…

Astrophysics of Galaxies · Physics 2025-09-04 Sam B. Ponnada

Recent advances on gamma-ray observations from SuperNova Remnants and Molecular Clouds offer the possibility to study in detail the properties of the propagation of escaping Cosmic Rays (CR). However, a complete theory for CR transport…

High Energy Astrophysical Phenomena · Physics 2015-09-09 Lara Nava , Stefano Gabici , Alexandre Marcowith , Giovanni Morlino , Vladimir Ptuskin

We present a suite of high-resolution cosmological simulations, using the FIRE-2 feedback physics together with explicit treatment of magnetic fields, anisotropic conduction and viscosity, and cosmic rays (CRs) injected by supernovae…

A correct description of cosmic-ray (CR) diffusion in turbulent plasma is essential for many astrophysical and heliospheric problems. This paper aims to present physical diffusion behavior of CRs in actual turbulent magnetic fields, model…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Siyao Xu , Huirong Yan

The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer self-consistently is key to the solution of many problems in numerical astrophysics. Such fluid flows are highly complex, rarely…

Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of cosmic ray transport. In this paper we use recently obtained scaling laws for MHD modes to obtain the scattering frequency for…

Astrophysics · Physics 2009-11-10 Huirong Yan , A. Lazarian

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

We discuss new methods to integrate the cosmic ray (CR) evolution equations coupled to magneto-hydrodynamics (MHD) on an unstructured moving mesh, as realised in the massively parallel AREPO code for cosmological simulations. We account for…

Astrophysics of Galaxies · Physics 2017-01-11 C. Pfrommer , R. Pakmor , K. Schaal , C. M. Simpson , V. Springel

Cosmic ray propagation is determined by the properties of interstellar turbulence. The multiphase nature of interstellar medium (ISM) and diversity of driving mechanisms give rise to spatial variation of turbulence properties. Meanwhile,…

High Energy Astrophysical Phenomena · Physics 2021-09-21 Huirong Yan

Cosmic ray (CR)-driven instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify magnetic fields and modulate CR transport so that the…

High Energy Astrophysical Phenomena · Physics 2021-03-03 Mohamad Shalaby , Timon Thomas , Christoph Pfrommer

The circumgalactic medium (CGM) plays a critical role in galaxy evolution, influencing gas flows, feedback processes, and galactic dynamics. Observations show a substantial cold gas reservoir in the CGM, but the mechanisms driving its…

Astrophysics of Galaxies · Physics 2025-06-11 Matthias Weber , Timon Thomas , Christoph Pfrommer , Ruediger Pakmor

Galaxy evolution is an important topic, and our physical understanding must be complete to establish a correct picture. This includes a thorough treatment of feedback. The effects of thermal-mechanical and radiative feedback have been…

Astrophysics of Galaxies · Physics 2023-07-13 Ellis R. Owen , Kinwah Wu , Yoshiyuki Inoue , H. -Y. Karen Yang , Alison M. W. Mitchell

A numerical method for integrating the equations describing a dynamically coupled system made of a fluid and cosmic-rays is developed. In smooth flows the effect of CR pressure is accounted for by modification of the characteristic…

Astrophysics · Physics 2008-11-26 Francesco Miniati

Astrophysical plasmas are turbulent and magnetized. The interaction between cosmic rays (CRs) and magnetohydrodynamic (MHD) turbulence is a fundamental astrophysical process. Based on the current understanding of MHD turbulence, we revisit…

High Energy Astrophysical Phenomena · Physics 2020-05-13 Siyao Xu , Alex Lazarian

We investigate the impact of cosmic rays (CRs) on galactic outflows from a multi-phase interstellar medium with solar neighbourhood conditions. The three-dimensional magneto-hydrodynamical simulations include CRs as a relativistic fluid in…

Astrophysics of Galaxies · Physics 2018-07-11 Philipp Girichidis , Thorsten Naab , Michał Hanasz , Stefanie Walch

Subsonic, compressive turbulence transfers energy to cosmic rays (CRs), a process known as non-resonant reacceleration. It is often invoked to explain observed ratios of primary to secondary CRs at $\sim \rm GeV$ energies, assuming wholly…

High Energy Astrophysical Phenomena · Physics 2023-01-23 Chad Bustard , S. Peng Oh

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