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The investigation of the diffusive transport of charged particles in a turbulent magnetic field remains a subject of considerable interest. Research has most frequently concentrated on determining the diffusion coefficient in the presence…

Since microscopic velocity diffusion can be incorporated into general relativity in a consistent way, we study cosmological background solutions when the diffusion phenomena takes place in an expanding universe. Our focus here relies on the…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-10 Hermano Velten , Simone Calogero

The origin of the extragalactic gamma-ray background is a pressing cosmological mystery. The Fermi Gamma-Ray Space Telescope has recently measured the intensity and spectrum of this background; both are substantially different from previous…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-16 Brian D. Fields , Vasiliki Pavlidou , Tijana Prodanovic

We present a new model of anisotropic cosmic ray propagation in the Milky Way, where cosmic rays are injected at discrete transient sources in the disc and propagated in the Galactic magnetic field. In the framework of our model, we show…

High Energy Astrophysical Phenomena · Physics 2023-05-18 G. Giacinti , D. Semikoz

Context: Typical space plasmas contain spatially and temporally variable turbulent electromagnetic fields. Understanding the transport of energetic particles and the acceleration mechanisms for charged particles is an important goal of…

High Energy Astrophysical Phenomena · Physics 2013-06-17 R. C. Tautz , I. Lerche , F. Kruse

The Fermi Gamma-ray Space Telescope has revealed a diffuse $\gamma$-ray background at energies from 0.1 GeV to 1 TeV, which can be separated into Galactic emission and an isotropic, extragalactic component. Previous efforts to understand…

High Energy Astrophysical Phenomena · Physics 2021-09-17 Matt A. Roth , Mark R. Krumholz , Roland M. Crocker , Silvia Celli

Cosmic ray (CR) propagation is controlled by scattering in turbulent magnetic fields in space. In general, diffusive propagation is governed by pitch-angle diffusion in phase space. In this study, pitch-angle diffusion in the local…

High Energy Astrophysical Phenomena · Physics 2026-05-26 Huirong Yan , Siqi Zhao , Ming Zhang

Cosmic rays, along with stellar radiation and magnetic fields, are known to make up a significant fraction of the energy density of galaxies such as the Milky Way. When cosmic rays interact in the interstellar medium, they produce gamma-ray…

Determining the physical mechanisms that extract energy from turbulent fluctuations in weakly collisional magnetized plasmas is necessary for a more complete characterization of the behavior of a variety of space and astrophysical plasmas.…

Plasma Physics · Physics 2017-08-02 Kristopher G. Klein , Gregory G. Howes , Jason M. TenBarge

Before being detected at Earth, charged cosmic rays propagate across the Solar System and undergo interactions with the turbulent solar wind and with the heliospheric magnetic field. As a result, they are subject to a series of processes…

High Energy Astrophysical Phenomena · Physics 2018-11-08 Andrea Vittino , Carmelo Evoli , Daniele Gaggero

The diffusive paradigm for the transport of Galactic cosmic rays is central to our understanding of the origin of these high energy particles. However, it is worth recalling that the normalization, energy dependence, and spatial extent of…

High Energy Astrophysical Phenomena · Physics 2018-07-11 Carmelo Evoli , Pasquale Blasi , Giovanni Morlino , Roberto Aloisio

The galactic diffuse $\gamma$-ray emission, as seen by Fermi Large Area Telescope (LAT), shows a sharp peak in the region around 4 kpc from the Galactic center, which can be interpreted either as due to an enhanced density of cosmic-ray…

High Energy Astrophysical Phenomena · Physics 2021-03-23 Giada Peron , Felix Aharonian , Sabrina Casanova , Ruizhi Yang , Roberta Zanin

The propagation of gamma-rays over cosmological distances is the subject of extensive theoretical and observational research at GeV and TeV energies. The mean free path of gamma-rays in the cosmic web is limited above 100 GeV due to the…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-11 J. Biteau , M. Meyer

This paper deals with the cosmic-ray penetration into molecular clouds and with the related gamma--ray emission. High energy cosmic rays interact with the dense gas and produce neutral pions which in turn decay into two gamma rays. This…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Stefano Gabici

It is well accepted today that diffusive acceleration in shocks results to the cosmic ray spectrum formation. This is in principle true for non-relativistic shocks, since there is a detailed theory covering a large range of their properties…

Astrophysics · Physics 2007-08-13 A. Meli , A. Mastichiadis

The physics of energetic particle propagation in magnetised environments plays a crucial role in both the processes of acceleration and transport of cosmic rays. Recent theoretical developments in the field of cosmic ray research have been…

High Energy Astrophysical Phenomena · Physics 2018-10-31 Elena Amato , Pasquale Blasi

We consider the astrophysical implications of the diffusion equation solution for Ultra-High Energy Cosmic Rays (UHECR) in the expanding universe, obtained in paper I (V.Berezinsky & A.Gazizov, ApJ 643 (2006) 8). The UHECR spectra are…

Astrophysics · Physics 2009-03-19 V. Berezinsky , A. Z. Gazizov

The circumgalactic medium (CGM) plays a crucial role in regulating material and energy exchange between galaxies and their environments. The best means of observing this medium is through absorption-line spectroscopy, but we have yet to…

Astrophysics of Galaxies · Physics 2025-06-24 Yue Hu , Evan Scannapieco , Edward Buie , Siyao Xu , Samuel T Sebastian , Om Biswal

An extensive program for the calculation of galactic cosmic-ray propagation has been developed. Primary and secondary nucleons, primary and secondary electrons, secondary positrons and antiprotons are included. Fragmentation and energy…

Astrophysics · Physics 2007-05-23 A. W. Strong , I. V. Moskalenko

Despite their discovery fifteen years ago, the nature and origin of the Fermi bubbles remain unclear. We here investigate the effect a magnetic field can have on a subsonic breeze outflow emanating from the Galactic centre region. The…

High Energy Astrophysical Phenomena · Physics 2026-03-18 Olivier Tourmente , Donna Rodgers-Lee , Andrew M. Taylor