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Cosmic rays (CR), constrained by scattering on magnetic irregularities, are believed to propagate diffusively. But a well-known defect of diffusive approximation whereby some of the particles propagate unrealistically fast has directed…

High Energy Astrophysical Phenomena · Physics 2016-10-11 Mikhail Malkov , Roald Sagdeev

In the interstellar medium of galaxies and the intracluster gas of galaxy clusters, the charged particles making up cosmic rays are moving almost exclusively along (but not across) magnetic field lines. The resulting anisotropic transport…

Astrophysics of Galaxies · Physics 2016-08-31 Ruediger Pakmor , Christoph Pfrommer , Christine M. Simpson , Rahul Kannan , Volker Springel

Under nonuniform convection, the distribution of diffusive particles can exhibit dipole and quadrupole anisotropy induced by the fluid inertial and shear force, respectively. These convection-related anisotropies, unlike the Compton-Getting…

High Energy Astrophysical Phenomena · Physics 2022-10-26 Yiran Zhang , Siming Liu , Dejin Wu

With the increasing use of ultrashort laser pulses and nanoscale-materials, one is regularly confronted to situations in which the properties of the media supporting propagation are not varying slowly with time (or space). Hence, the usual…

Other Condensed Matter · Physics 2009-11-10 Guillaume Petite , Alexander Shvartsburg

Shortfalls in cosmic ray (CR) propagation models obscure the CR sources and acceleration mechanisms. This problem became particularly obvious after the Fermi, Pamela, and AMS-02 have discovered the electron/positron and $p/$He spectral…

High Energy Astrophysical Phenomena · Physics 2017-03-09 Mikhail Malkov

We revisit propagation of galactic cosmic rays (CRs) in light of recent advances in CR diffusion theory in realistic interstellar turbulence. We use a tested model of turbulence in which it has been shown that fast modes dominate scattering…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Carmelo Evoli , Huirong Yan

Using hybrid simulations (kinetic ions--fluid electrons), we test the linear theory predictions of the cosmic ray (CR) streaming instability. We consider two types of CR distribution functions: a "hot" distribution where CRs are represented…

High Energy Astrophysical Phenomena · Physics 2019-09-16 Colby Haggerty , Damiano Caprioli , Ellen Zweibel

The propagation of charged cosmic rays through the Galactic environment influences all aspects of the observation at Earth. Energy spectrum, composition and arrival directions are changed due to deflections in magnetic fields and…

Instrumentation and Methods for Astrophysics · Physics 2017-07-26 Lukas Merten , Julia Becker Tjus , Horst Fichtner , Björn Eichmann , Günter Sigl

We solve the radiative transfer equation (RTE) in anisotropically scattering media as an infinite series. Each series term represents a distinct number of scattering events, with analytical solutions derived for zero and single scattering.…

High Energy Physics - Phenomenology · Physics 2024-07-25 Vladimir Allakhverdian , Dmitry V. Naumov

Cosmic ray (CR) feedback plays a vital role in shaping the formation and evolution of galaxies through their interaction with magnetohydrodynamic waves. In the CR self-confinement scenario, the waves are generated by the CR gyro-resonant…

High Energy Astrophysical Phenomena · Physics 2025-07-23 Xiaochen Sun , Xue-Ning Bai , Xihui Zhao

In the standard diffusive picture for transport of cosmic rays (CRs), a gradient in the CR density induces a typically small, dipolar anisotropy in their arrival directions. This has been widely advertised as a tool for finding nearby…

High Energy Astrophysical Phenomena · Physics 2015-01-15 Philipp Mertsch , Stefan Funk

We come back to the analytical solution of the standard transfer problem in a stellar atmosphere. It consists in solving the radiative transfer equation in a homogeneous and isothermal plane-parallel atmosphere, with light scattering taken…

Astrophysics · Physics 2007-05-23 L. Chevallier , B. Rutily

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

Cosmic rays (CRs) are an integral part of the non-thermal pressure budget in the interstellar medium (ISM) and are the leading-order ionization mechanism in cold molecular clouds. We study the impacts that different microphysical CR…

Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of nearby galaxies, but many of their properties are not well-constrained. Gamma-ray observations provide a powerful tool in this respect, allowing us to constrain both the…

High Energy Astrophysical Phenomena · Physics 2023-07-19 Maria Werhahn , Philipp Girichidis , Christoph Pfrommer , Joseph Whittingham

A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a…

General Relativity and Quantum Cosmology · Physics 2018-01-24 B. V. Ivanov

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…

Dynamically, cosmic rays with energies above about one GeV/nucleon may be important agents of galaxy evolution. Their pressures compare with the thermal and magnetic ones impacting galactic gas accretion, fountains and galactic outflows,…

High Energy Astrophysical Phenomena · Physics 2022-05-18 A. Nuñez-Castiñeyra , I. A. Grenier , F. Bournaud , Y. Dubois , F. R. Kamal Youssef , P. Hennebelle

For an equation of state in which pressure is a function only of density, the analysis of Newtonian stellar structure is simple in principle if the system is axisymmetric, or consists of a corotating binary. It is then required only to…

Solar and Stellar Astrophysics · Physics 2010-08-12 Richard H. Price , Charalampos Markakis , John L. Friedman

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