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Department of Physics

Staff profile

Publication details for Prof Sir Arnold Wolfendale

Erlykin, AD, Lagutin, AA & Wolfendale, AW (2003). Properties of the interstellar medium and the propagation of cosmicrays in the Galaxy. Astroparticle Physics 19(3): 351-362.
  • Publication type: Journal Article
  • ISSN/ISBN: 0927-6505
  • Keywords: ANOMALOUS DIFFUSION; SUPERNOVA-REMNANTS; GAMMA-RAYS; ACCELERATION;SPECTRUM; ENERGY; DENSITY; ORIGIN; RADIATION; EMISSION

Author(s) from Durham

Abstract

The problem of the origin of cosmic rays in the shocks produced by
supernova explosions at energies below the so-called 'knee' (at similar
to3 x 10(6) GeV) in the energy spectrum is addressed, with special
attention to the propagation of the particles through the inhomogeneous
interstellar medium (ISM) and the need to explain recent anisotropy
results [Proc. 27th Int. Conf. Cosmic Rays, Hamburg 1 (2001) 10]. 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
(e.g. 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
the cosmic ray halo. Anomalous diffusion allows an explanation of the
recent important result from the Chacaltaya extensive air shower
experiment [Proc. 27th Int. Conf. Cosmic Rays, Hamburg 1 (2001) 101,
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.
(C) 2002 Elsevier Science B.V. All rights reserved.