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| Titel |
Cosmic rays and stochastic magnetic reconnection in the heliotail |
| VerfasserIn |
P. Desiati, A. Lazarian |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 19, no. 3 ; Nr. 19, no. 3 (2012-06-19), S.351-364 |
| Datensatznummer |
250014213
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| Publikation (Nr.) |
 copernicus.org/npg-19-351-2012.pdf |
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| Zusammenfassung |
| Galactic cosmic rays are believed to be generated by diffusive shock
acceleration processes in Supernova Remnants, and the arrival direction is
likely determined by the distribution of their sources throughout the Galaxy,
in particular by the nearest and youngest ones. Transport to Earth through
the interstellar medium is expected to affect the cosmic ray properties as
well. However, the observed anisotropy of TeV cosmic rays and its energy
dependence cannot be explained with diffusion models of particle propagation
in the Galaxy. Within a distance of a few parsec, diffusion regime is not
valid and particles with energy below about 100 TeV must be influenced by
the heliosphere and its elongated tail. The observation of a highly
significant localized excess region of cosmic rays from the apparent
direction of the downstream interstellar flow at 1–10 TeV energies might
provide the first experimental evidence that the heliotail can affect the
transport of energetic particles. In particular, TeV cosmic rays propagating
through the heliotail interact with the 100–300 AU wide magnetic field
polarity domains generated by the 11 yr cycles. Since the strength of
non-linear convective processes is expected to be larger than viscous
damping, the plasma in the heliotail is turbulent. Where magnetic field
domains converge on each other due to solar wind gradient, stochastic
magnetic reconnection likely occurs. Such processes may be efficient enough
to re-accelerate a fraction of TeV particles as long as scattering processes
are not strong. Therefore, the fractional excess of TeV cosmic rays from the
narrow region toward the heliotail direction traces sightlines with the
lowest smearing scattering effects, that can also explain the observation of
a harder than average energy spectrum. |
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