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38th COSPAR Scientific Assembly (Cospar10), Bremen : Allemagne (2010)
A Markov Chain Monte Carlo technique for Galactic cosmic-ray physics
A. Putze, D. Maurin1, L. Derome2

We implemented a Markov Chain Monte Carlo technique to estimate the probability-density functions of the cosmic-ray transport and source parameters in a diffusion model. From the measurement of the B/C ratio and radioactive cosmic-ray clocks, we calculate their probability density functions, with a special emphasis on the halo size L of the Galaxy and the local underdense bubble of size rh . The B/C analysis leads to a most probable diffusion slope δ = 0.86+0.04 for a diffusion model including convection and reacceleration. A combined fit -0.04 on B/C and the isotopic ratios (10 Be/9 Be, 26 Al/27 Al, 36 Cl/Cl) leads to L = 8+8 kpc and -7 rh = 120+20 pc. This value for rh is consistent with direct measurements of the local interstellar -20 medium. The size of the diffusive halo depends crucially on the value of the diffusion slope δ, and also on the presence/absence of the local underdensity damping effect on radioactive nuclei.
1 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
2 :  LPSC - Laboratoire de Physique Subatomique et de Cosmologie
Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Physique/Astrophysique/Instrumentation et méthodes pour l'astrophysique

Planète et Univers/Astrophysique/Instrumentation et méthodes pour l'astrophysique