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The H$_2$ ionisation rate in the central molecular zone, located in the Galactic centre, is estimated to be $\zeta\sim2\times10^{-14}~\mathrm{s}^{-1}$, based on observations of H$_3^+$ lines. This value is two to three orders of magnitude…

High Energy Astrophysical Phenomena · Physics 2025-02-12 Sruthiranjani Ravikularaman , Sarah Recchia , Vo Hong Minh Phan , Stefano Gabici

We consider the propagation of galactic cosmic rays in the fractal interstellar medium. Steady state solution of the fractional diffusion equation, describing cosmic ray propagation, is found. We show that the exponent of the steady state…

Astrophysics · Physics 2007-05-23 A. A. Lagutin , V. V. Makarov , A. G. Tyumentsev

We consider the propagation of galactic cosmic rays under assumption that the interstellar medium is a fractal one. An anomalous diffusion equation in terms of fractional derivatives is used to describe of cosmic ray propagation. The…

Astrophysics · Physics 2007-05-23 A. A. Lagutin , V. V. Uchaikin

We calculate the energy spectra and mass composition of cosmic rays in energy region 1 - 10^8 GeV/particle under the assumption that cosmic rays propagation in the Galaxy is described by anomalous diffusion equation. Our results and…

Astrophysics · Physics 2007-05-23 A. A. Lagutin , D. V. Strelnikov , A. G. Tyumentsev

The propagation of cosmic-ray protons in the Galaxy is discussed under the framework of a three dimensional convection-diffusion model. Starting with the assumption of a uniform and continuous distribution of cosmic-ray sources injecting…

Astrophysics · Physics 2009-11-11 Thoudam Satyendra

We study the spectral properties of the cosmic-ray spectrum in the interstellar medium within 1 kpc distance from the Sun. We used eight-year exposure data of molecular clouds of the Gould Belt obtained with the Fermi/LAT telescope to…

High Energy Astrophysical Phenomena · Physics 2017-10-04 Andrii Neronov , Denys Malyshev , Dmitri V. Semikoz

We fit the ultra high energy cosmic ray spectra above 10$^{19}$ eV with different injection spectra at cosmic ray sources that are uniformly and homogeneously distributed in the Universe. We conclude that the current UHE spectra are…

Astrophysics · Physics 2011-05-12 Daniel De Marco , Todor Stanev

Cosmic rays are a fundamental source of ionization for molecular and diffuse clouds, influencing their chemical, thermal, and dynamical evolution. The amount of cosmic rays inside a cloud also determines the $\gamma$-ray flux produced by…

High Energy Astrophysical Phenomena · Physics 2015-09-18 G. Morlino , S. Gabici , J. Krause

We consider the problem of the cosmic ray spectrum formation assuming that cosmic rays are produced by Galactic sources. The anomalous diffusion equation proposed in our recent papers is used to describe cosmic ray propagation in the…

High Energy Astrophysical Phenomena · Physics 2019-05-17 Nikolay Volkov , Anatoly Lagutin , Alexander Tyumentsev , Roman Raikin

Recent data from ATIC, CREAM and PAMELA indicate that the cosmic ray energy spectra of protons and nuclei exhibit a remarkable hardening at energies above 100 GeV per nucleon. We propose that the hardening is an interstellar propagation…

High Energy Astrophysical Phenomena · Physics 2012-05-29 N. Tomassetti

Cosmic rays (CRs) are an integral component of the interstellar medium, producing broadband emission while interacting with other Galactic matter components like the interstellar gas or magnetic fields. In addition to observations,…

High Energy Astrophysical Phenomena · Physics 2022-10-12 Julia Thaler , Ralf Kissmann , Olaf Reimer

Cosmic rays fill up the entire volume of galaxies, providing an important source of heating and ionisation of the interstellar medium, and may play a significant role in the regulation of star formation and galactic evolution. Diffuse…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Troy A. Porter

Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…

Astrophysics · Physics 2007-05-23 Martin Pohl

We develop a theory to account for the cosmic ray spectrum between 1 GeV and 10^4 GeV following the earlier papers of this series. We use the basic concept that the cosmic ray particles are accelerated in a supernova shock that travels…

Astrophysics · Physics 2007-05-23 Peter L. Biermann , Richard G. Strom

In a previous study (Maurin et al., 2001), we explored the set of parameters describing diffusive propagation of cosmic rays (galactic convection, reacceleration, halo thickness, spectral index and normalization of the diffusion…

Astrophysics · Physics 2009-11-07 David Maurin , Richard Taillet , Fiorenza Donato

Galactic transport models for cosmic rays involve the diffusive motion of these particles in the interstellar medium. Due to the large-scale structured galactic magnetic field this diffusion is anisotropic with respect to the local field…

High Energy Astrophysical Phenomena · Physics 2013-06-07 Frederic Effenberger , Horst Fichtner , Klaus Scherer , Ingo Büsching

The spectral data on the diffuse Galactic gamma-rays, at medium and high latitudes (|b| > 10) and energies of 1-100 GeV, recently published by the Fermi Collaboration are used to produce a novel study on the gamma-ray emissivity in the…

High Energy Astrophysical Phenomena · Physics 2011-10-28 Maryam Tavakoli , Ilias Cholis , Carmelo Evoli , Piero Ullio

We present our new model for the description of the very high energy Galactic gamma-ray emission based on a discrete injection of cosmic rays by individual sources. We investigate the morphology of the very high energy gamma-ray sky, the…

High Energy Astrophysical Phenomena · Physics 2025-01-13 Samy Kaci , Gwenael Giacinti

Cosmic ray propagation is diffusive because of pitch angle scattering by waves. We demonstrate that if the high-amplitude magnetohydrodynamic turbulence with $\tilde B/\langle B\rangle \sim 1$ is present on top of the mean field gradient,…

High Energy Astrophysical Phenomena · Physics 2015-09-30 Mikhail V. Medvedev , Viktor V. Medvedev

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