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The arrival directions of TeV-PeV cosmic rays are remarkably uniform due to the isotropization of their directions by scattering on turbulent magnetic fields. Small anisotropies can exist in standard diffusion models, however, only on the…

High Energy Astrophysical Phenomena · Physics 2022-03-14 Marco Kuhlen , Vo Hong Minh Phan , Philipp Mertsch

We present a parameter study of the magnetohydrodynamical dynamo driven by cosmic rays in the interstellar medium (ISM) focusing on the efficiency of magnetic field amplification and the issue of energy equipartition between magnetic,…

Astrophysics · Physics 2015-05-13 Michał Hanasz , Katarzyna Otmianowska-Mazur , Grzegorz Kowal , Harald Lesch

We employ a data-driven approach to investigate the rigidity and spatial dependence of the diffusion of cosmic rays in the turbulent magnetic field of the Milky Way. Our analysis combines data sets from the experiments Voyager, AMS-02,…

High Energy Astrophysical Phenomena · Physics 2024-04-24 Mattia Di Mauro , Michael Korsmeier , Alessandro Cuoco

Interpretations of synchrotron observations often assume a tight correlation between magnetic and cosmic ray energy densities. We examine this assumption using both test-particle simulations of cosmic rays and MHD simulations which include…

Astrophysics of Galaxies · Physics 2018-10-10 Amit Seta , Anvar Shukurov , Paul J. Bushby , Toby S. Wood

Cosmic rays passing through large astrospheres can be efficiently cooled inside these "cavities" in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front of the astrospherical bow…

We consider anisotropic diffusion of Galactic cosmic rays in the Galactic magnetic field, using the Jansson-Farrar model for the field. In this paper we investigate the influence of source position on the cosmic ray flux at Earth in two…

Astrophysics of Galaxies · Physics 2020-01-29 A. AL-Zetoun , A. Achterberg

The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate…

High Energy Astrophysical Phenomena · Physics 2018-04-11 R. Farber , M. Ruszkowski , H. -Y. K. Yang , E. G. Zweibel

Diffusion of cosmic rays (CRs) is the key process of understanding their propagation and acceleration. We employ the description of spatial separation of magnetic field lines in MHD turbulence in Lazarian & Vishniac (1999) to quantify the…

High Energy Astrophysical Phenomena · Physics 2016-12-21 A. Lazarian , Huirong Yan

Using a hybrid kinetic magnetohydrodynamic formalism incorporating the effects of pressure anisotropy, we simulate the evolution of a turbulent collisionless plasma in six different models covering the sub/super-sonic and…

High Energy Astrophysical Phenomena · Physics 2013-12-31 M. S. Nakwacki , J. Peralta-Ramos

The arrival directions of multi-TeV cosmic rays show significant anisotropies at small angular scales. It has been argued that this small scale structure is reflecting the local, turbulent magnetic field in the presence of a global dipole…

High Energy Astrophysical Phenomena · Physics 2015-12-01 Philipp Mertsch , Markus Ahlers

The diffusive motion of charged particles in synthetic magnetic turbulence with different properties is investigated by using numerical simulations with unprecedented dynamical range, which allow us to ensure that both the inertial range…

High Energy Astrophysical Phenomena · Physics 2020-11-24 Andrej Dundovic , Oreste Pezzi , Pasquale Blasi , Carmelo Evoli , William H. Matthaeus

Galactic cosmic ray transport relies on the existence of turbulence on scales comparable with the gyration radius of the particles and with wavenumber vector oriented along the local magnetic field. In the standard picture, in which…

High Energy Astrophysical Phenomena · Physics 2023-12-29 O. Pezzi , P. Blasi

We extend previous studies of mixed-composition extragalactic cosmic-ray source models, by investigating the influence of a non-negligible extragalactic magnetic field on the propagated cosmic-ray spectrum and composition. We study the…

Astrophysics · Physics 2009-11-13 N. Globus , D. Allard , E. Parizot

The physics of cosmic rays (CR) is a promising candidate for explaining the driving of galactic winds and outflows. Recent galaxy formation simulations have demonstrated the need for active CR transport either in the form of diffusion or…

Astrophysics of Galaxies · Physics 2016-07-19 Ruediger Pakmor , Christoph Pfrommer , Christine M. Simpson , Volker Springel

We introduce a static toy model of the cosmic ray (CR) universe in which cosmic ray propagation is taken to be diffusive and cosmic ray sources are distributed randomly with a density the same as that of local L* galaxies, $5 \times…

Astrophysics · Physics 2007-10-29 Roger Clay , Roland M. Crocker

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

Recent direct measurements of Galactic cosmic ray spectra by balloon/space-borne detectors reveal spectral hardenings of all major nucleus species at rigidities of a few hundred GV. The all-sky diffuse gamma-ray emissions measured by the…

High Energy Astrophysical Phenomena · Physics 2018-03-21 Yi-Qing Guo , Qiang Yuan

The propagation of TeV-PeV cosmic rays (CR) in our Galaxy can be described as a diffusive process. We discuss here two effects, with important observational consequences, that cannot be predicted by the diffusion approximation in its usual…

High Energy Astrophysical Phenomena · Physics 2014-12-01 G. Giacinti

We argue that the diffusion of cosmic rays in the Galactic magnetic field has to be strongly anisotropic. As a result, the number of CR sources contributing to the local CR flux is reduced by a factor $\sim 200$. The CR density is therefore…

High Energy Astrophysical Phenomena · Physics 2019-05-22 M. Kachelriess

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