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Supernova remnants (SNRs) are one of the most energetic astrophysical events and are thought to be the dominant source of Galactic cosmic rays (CRs). A recent report on observations from the Fermi satellite has shown a signature of pion…

High Energy Astrophysical Phenomena · Physics 2015-08-26 Soonyoung Roh , Shu-ichiro Inutsuka , Tsuyoshi Inoue

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

The transport of charged particles in various astrophysical environments permeated by magnetic fields is described in terms of a diffusion process, which relies on diffusion-tensor parameters generally inferred from Monte-Carlo simulations.…

High Energy Astrophysical Phenomena · Physics 2021-10-20 Olivier Deligny

We give a review of cosmic ray propagation models. It is shown that the development of the theory of cosmic ray origin leads inevitably to the conclusion that cosmic ray propagation in the Galaxy is determined by effective particle…

High Energy Astrophysical Phenomena · Physics 2009-05-20 V. Dogiel , D. Breitschwerdt

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

Recent data from ATIC, CREAM and PAMELA revealed that the energy spectra of cosmic ray (CR) nuclei above 100 GeV/nucleon experience a remarkable hardening with increasing energy. This effect cannot be recovered by the conventional…

High Energy Astrophysical Phenomena · Physics 2015-06-11 N. Tomassetti

We compute the contribution from clusters of galaxies to the diffuse neutrino and $\gamma-$ray background. Due to their unique magnetic-field configuration, cosmic rays (CRs) with energy $\leq10^{17}$ eV can be confined within these…

High Energy Astrophysical Phenomena · Physics 2023-08-01 Saqib Hussain , Giulia Pagliaroli , Elisabete M. de Gouveia Dal Pino

Molecular clouds are complex magnetized structures, with variations over a broad range of length scales. Ionization in dense, shielded clumps and cores of molecular clouds is thought to be caused by charged cosmic rays (CRs). These CRs can…

Astrophysics of Galaxies · Physics 2021-07-27 Ellis R. Owen , Alvina Y. L. On , Shih-Ping Lai , Kinwah Wu

Understanding how cosmic rays (CRs) propagate within the giant molecular clouds (GMCs) is critical for studying the dynamics and chemical processes inside the clouds. The flux of low-energy CRs inside the dense cores of GMCs strongly…

High Energy Astrophysical Phenomena · Physics 2024-12-03 Zhaodong Shi , Bing Liu , Rui-zhi Yang

The majority of galactic baryons reside outside of the galactic disk in the diffuse gas known as the circumgalactic medium (CGM). While state-of-the art simulations excel at reproducing galactic disk properties, many struggle to drive…

Astrophysics of Galaxies · Physics 2018-12-05 Iryna Butsky , Thomas R. Quinn

The spectrum and morphology of the diffuse Galactic gamma-ray emission carries valuable information on cosmic ray (CR) propagation. Recent results obtained by analyzing Fermi-LAT data accumulated over seven years of observation show a…

High Energy Astrophysical Phenomena · Physics 2016-08-05 S. Recchia , P. Blasi , G. Morlino

Cosmic-ray (CR) physics has been a prolific field of research for over a century. The open problems related to CR acceleration, transport and modulation are deeply connected with the indirect searches for particle dark matter (DM). In…

High Energy Astrophysical Phenomena · Physics 2016-01-12 Daniele Gaggero

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

Cosmic-ray transport in turbulent astrophysical environments remains a multifaceted problem and, despite decades of study, the impact of complex magnetic field geometry -- evident in simulations and observations -- has only recently…

Recently, the {\it{Fermi}} space telescope has discovered two large $\gamma$-ray emission regions, the so-called "Fermi bubbles", that extend up to $\sim 50^\circ$ above and below the Galactic center. The $\gamma$-ray emission from the…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Satyendra Thoudam

A major uncertainty in understanding the transport and feedback of cosmic-rays (CRs) within and beyond our Galaxy lies in the unknown CR scattering rates, which are primarily determined by wave-particle interaction at microscopic…

High Energy Astrophysical Phenomena · Physics 2022-04-06 Xue-Ning Bai

Cosmic rays (CRs) and magnetic fields may be dynamically important in driving large-scale galactic outflows from rapidly star-forming galaxies. We construct two-dimensional axisymmetric models of the local starburst and super-wind galaxy…

Astrophysics of Galaxies · Physics 2020-04-29 Benjamin J. Buckman , Tim Linden , Todd A. Thompson

We discuss some aspects of the propagation of high-energy cosmic rays (CRs) in turbulent magnetic fields, and propose a formula for the diffusion coefficient based on accurate simulations in a wide energy range. We discuss the transition…

Astrophysics · Physics 2009-11-10 Etienne Parizot

The theory of Galactic Winds, driven by the cosmic-ray pressure gradient, is reviewed both on the magnetohydrodynamic and on the kinetic level. In this picture the magnetic field of the Galaxy above the dense gas disk is assumed to have a…

High Energy Astrophysical Phenomena · Physics 2014-11-06 Heinrich J. Völk

Cosmic rays (CRs) play a pivotal role in various astrophysical systems, delivering feedback over a broad range of scales. However, modeling CR transport remains challenging due to its inherently multi-scale nature and complex microphysics.…

High Energy Astrophysical Phenomena · Physics 2026-02-05 Xihui Zhao , Xue-Ning Bai , Eve C. Ostriker