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Despite many efforts to find a reasonable explanation, the origin of the "knee" in the cosmic ray spectrum at energy around 10**15.5 eV remains mysterious. In this letter we suggest that the "knee" may be due to a GZK-like effect of cosmic…

Astrophysics · Physics 2007-05-23 M. T. Dova , L. N. Epele , J. D. Swain

We study the formation of galactic outflows from supernova explosions (SNe) with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different…

Scenarios in which the knee of the cosmic ray spectrum depends on the particle rigidities usually predict that the cosmic ray composition becomes heavier above the knee and have associated a change in the spectral slope of each individual…

Astrophysics · Physics 2009-11-10 Julián Candia , Esteban Roulet

After more than a century of discovering cosmic rays, a comprehensive description of their origin, propagation, and composition still eludes us. One of the difficulties is that these particles interact with magnetic fields; therefore, their…

High Energy Astrophysical Phenomena · Physics 2023-07-13 Vanessa López-Barquero , Paolo Desiati

Both the acceleration of cosmic rays (CR) in supernova remnant shocks and their subsequent propagation through the random magnetic field of the Galaxy deem to result in an almost isotropic CR spectrum. Yet the MILAGRO TeV observatory…

Astrophysics of Galaxies · Physics 2010-09-03 M. A. Malkov , P. H. Diamond , L. 'O. C. Drury , R. Z. Sagdeev

The transport of energetic particles such as Cosmic Rays is governed by the properties of the plasma being traversed. While these properties are rather poorly known for galactic and interstellar plasmas due to the lack of in situ…

Solar and Stellar Astrophysics · Physics 2014-06-03 Tobias Wiengarten , Jens Kleimann , Horst Fichtner , Patrick Kühl , Andreas Kopp , Bernd Heber , Ralf Kissmann

Recent cosmic ray (CR) measurements have revealed unexpected anomalies in secondary CRs, namely deviations from the predictions of the so-called standard Galactic CR paradigm regarding the composition and energy spectra of the products of…

High Energy Astrophysical Phenomena · Physics 2024-10-30 Rui-zhi Yang , Felix Aharonian

Radio continuum observations of external galaxies provide us with an excellent outside view on the distribution of cosmic-ray electrons in the disc and halo. In this review, we summarise the current state of what we have learned from…

Astrophysics of Galaxies · Physics 2021-12-16 Volker Heesen

We construct a Galactic cosmic ray (CR) diffusion model while considering that CR sources reside predominantly in the Galactic spiral arms. We find that the CR flux (CRF) reaching the solar system should periodically increase each crossing…

Astrophysics · Physics 2008-11-26 Nir J. Shaviv

Spectra of Cosmic Rays (CRs), particularly their features, may hold essential information about astroparticle and fundamental physics. Realizing that both $4$ PeV CR knee and electron's TeV break have nearly identical Lorentz factor, i.e.…

High Energy Astrophysical Phenomena · Physics 2018-09-03 Chao Jin , Wei Liu , Hong-Bo Hu , Yi-Qing Guo

The theory of first order Fermi acceleration at shocks assumes that particles diffuse due to scattering off slow-moving magnetic irregularities. However, cosmic rays are closely tied to magnetic field lines, and the transport process,…

Astrophysics · Physics 2011-05-23 P. Duffy , J. G. Kirk , Y. A. Gallant , R. O. Dendy

We examine the cosmic-ray protons (CRp) accelerated at collisionless shocks in galaxy clusters using cosmological structure formation simulations. We find that in the intracluster medium (ICM) within the virial radius of simulated clusters,…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Ji-Hoon Ha , Dongsu Ryu , Hyesung Kang

A crucial process in Galactic cosmic-ray (CR) transport is the spatial diffusion due to the interaction with the interstellar turbulent magnetic field. Usually, CR diffusion is assumed to be uniform and isotropic all across the Galaxy.…

High Energy Astrophysical Phenomena · Physics 2017-10-25 Silvio Sergio Cerri , Daniele Gaggero , Andrea Vittino , Carmelo Evoli , Dario Grasso

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

Context. Galactic cosmic rays are widely assumed to arise from diffusive shock acceleration, specifically at shocks in supernova remnants (SNRs). These shocks expand in a complex environment, particularly in the core-collapse scenario as…

High Energy Astrophysical Phenomena · Physics 2022-05-25 Samata Das , Robert Brose , Dominique M. -A. Meyer , Martin Pohl , Iurii Sushch , Pavlo Plotko

We review progress in high-energy cosmic ray physics focusing on recent experimental results and models developed for their interpretation. Emphasis is put on the propagation of charged cosmic rays, covering the whole range from $\sim…

High Energy Astrophysical Phenomena · Physics 2020-01-16 M. Kachelriess , D. V. Semikoz

We have carried out a detailed study to understand the observed energy spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our study shows that a single Galactic component with subsequent energy cut-offs in the individual…

High Energy Astrophysical Phenomena · Physics 2016-11-15 S. Thoudam , J. P. Rachen , A. van Vliet , A. Achterberg , S. Buitink , H. Falcke , J. R. Hörandel

The Galactic cosmic ray (GCR) intensity has been postulated by others to vary cyclically with a peak to valley ratio of ~3:1, as the Solar System moves from the Spiral Arm to the Inter-Arm regions of the Galaxy. These intensities have been…

Solar and Stellar Astrophysics · Physics 2015-06-15 T. Sloan , A. W. Wolfendale

While it is well-known that cosmic rays (CRs) can gain energy from turbulence via second order Fermi acceleration, how this energy transfer affects the turbulent cascade remains largely unexplored. Here, we show that damping and steepening…

High Energy Astrophysical Phenomena · Physics 2023-08-15 Chad Bustard , S. Peng Oh

The microphysics of ~GeV cosmic ray (CR) transport on galactic scales remain deeply uncertain, with almost all studies adopting simple prescriptions (e.g. constant-diffusivity). We explore different physically-motivated, anisotropic,…

High Energy Astrophysical Phenomena · Physics 2022-03-18 Philip F. Hopkins , Jonathan Squire , T. K. Chan , Eliot Quataert , Suoqing Ji , Dusan Keres , Claude-Andre Faucher-Giguere
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