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Article Dans Une Revue The Astrophysical Journal Année : 2004

The Effects of Discreteness of Galactic Cosmic-Ray Sources

Résumé

Most studies of GeV Galactic cosmic-ray (GCR) nuclei assume a steady state/continuous distribution for the sources of cosmic rays, but this distribution is actually discrete in time and space. The current progress in our understanding of cosmic-ray physics (acceleration, propagation), the need for a consistent explanation of several properties of GCRs (nuclei, γ, etc.), and the precision of present and future space missions (e.g., INTEGRAL, AMS, AGILE, GLAST) point toward the necessity to go beyond this approximation. A steady state semianalytical model that well describes many nuclei data has been developed in the past years based on this approximation, as well as others. We wish to extend it to a time-dependent version, including discrete sources. As a first step, the validity of several approximations of the model we use is checked to validate the approach: (1) the effect of the radial variation of the interstellar gas density is inspected and (2) the effect of a specific modeling for the Galactic wind (linear vs. constant) is discussed. In a second step, the approximation of using continuous sources in space is considered. This is completed by a study of time discreteness through the time-dependent version of the propagation equation. A new analytical solution of this equation for instantaneous pointlike sources, including the effect of escape, Galactic wind, and spallation, is presented. Application of time and space discreteness to definite propagation conditions and realistic distributions of sources will be presented in a future paper.

Dates et versions

hal-04111315 , version 1 (31-05-2023)

Identifiants

Citer

R. Taillet, P. Salati, D. Maurin, E. Vangioni-Flam, M. Cassé. The Effects of Discreteness of Galactic Cosmic-Ray Sources. The Astrophysical Journal, 2004, 609, pp.173-185. ⟨10.1086/421059⟩. ⟨hal-04111315⟩
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