Properties of the Interstellar Medium and the Propagation of Cosmic Rays in the Galaxy

Abstract

The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so called 'knee' (at ~3*10${}^6$ GeV) in the energy spectrum is addressed, with special attention to the propagation of the particles through the inhomogenious interstellar medium and the need to explain recent anisotropy results, [1]. It is shown that the fractal character of the matter density and magnetic field distribution leads to the likelihood of a substantial increase of spatial fluctuations in the cosmic ray energy spectra. While the spatial distribution of cosmic rays in the vicinity of their sources (eg. inside the Galactic disk) does not depend much on the character of propagation and is largely determined by the distribution of their sources, the distribution at large distances from the Galactic disk depends strongly on the character of the propagation. In particular, the fractal character of the ISM leads to what is known as 'anomalous diffusion' and such diffusion helps us to understand the formation of Cosmic Ray Halo. Anomalous diffusion allows an explanation of the recent important result from the Chacaltaya extensive air shower experiment [1], viz. a Galactic Plane Enhancement of cosmic ray intensity in the Outer Galaxy, which is otherwise absent for the case of the so-called 'normal' diffusion. All these effects are for just one reason: anomalous diffusion emphasizes the role of local phenomena in the formation of cosmic ray characteristics in our Galaxy and elsewhere.

18 pages, 5 figures, accepted by Astropartoicle Physics

References in corpus (2)

• Transport of Cosmic Rays in Chaotic Magnetic Fields
• A Fractal Analysis of the HI Emission from the Large Magellanic Cloud

Cited by in corpus (16)

• The Anisotropy of Galactic Cosmic Rays as a Product of Stochastic Supernova Explosions
• Cosmic rays and climate change over the past 1000 million years
• Cosmic Rays and the Monogem Supernova Remnant
• Cosmic Rays in the Inner Galaxy and the Diffusion Properties of the Interstellar Medium
• The Origin of Cosmic Rays
• Gamma Rays frim the Galactic Centre
• Leaky-box approximation to the fractional diffusion model of cosmic rays
• Cosmic ray antiprotons and the Single Source model
• The Local Bubble in the interstellar medium and the origin of the low energy cosmic rays
• The role of the Galactic Halo and the Single Source in the formation of the cosmic ray anisotropy
• Cosmic ray anisotropies to 5 PeV
• Calculations of CR energy spectra within the NoRD model
• Particle Spectra and Mass Composition in the Ultra-High Energy Region in the Framework of the Galactic Origin of Cosmic Rays
• Average value of the cosmic ray injection exponent at Galactic sources
• Spectra of protons and nuclei in the energy range of $10^{10}÷10^{20}$ eV in the framework of Galactic cosmic ray origin
• Structures in the cosmic ray energy spectra