Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

Table 15.2: Former PhD students of the SHERPA group.
Name PhD thesis Current position
Françoise Rosso 1994 teacher (classes préparatoires)
Jonathan Ferreira 1994 assistant professor in the group
Alexandre Marcowith 1996 CNRS position at CESR-Toulouse
Pierre-Olivier Petrucci 1998 CNRS position in the group
Nicolas Renaud 1999 teacher (classes préparatoires)
Evy Kersalé 2000 postdoctoral position at Leeds-Cambridge
Fabien Casse 2001 assistant professor at Paris VII
Denis Gialis 2004 engineer at ONERA
Ludovic Saugé 2004 postdoctoral position at IPN-Lyon
• GLAST: the whole team is involved in the scientific support. With an overlap with the HESS window,
this mission should provide invaluable clues on compact objects and GRBs.
• ECLAIRS: G. Henri and G. Pelletier are involved in the scientific support of this instrument with the
goal of studying the prompt emission of GRBs.
• HESS: G. Henri, G. Pelletier, P.-O. Petrucci are deeply involved in the HESS collaboration where they
provide a scientific support, especially for the interpretation of Blazar observations and multi-wavelength
approaches. This Astroparticle experiment is very successful (cf. papers in Nature, Science...) and is
opening a new window of astrophysics.
15.10 Doctoral formation and Schools
The SHERPA team is heavily involved in teaching activities through the presence of 3 teachers (out of 6
permanent members), including 2 professors who have benefitted from a position at the prestigious Institut
Universitaire de France. One of them, G. Henri, is the current director for the ”Master 2 Recherche Astrophysique
et Milieux Dilués”, which is the pre-doctoral year before French thesis.
The group has regularly formed PhD thesis students who found good academic or industrial positions for
most of them (see Table 2).
Members of the team have also organized schools for researchers. G. Henri, G. Pelletier and F. Ménard
(FOST) organized a school on ”Accretion disks, jets and high-energy phenomena in astrophysics” in 2002 at
Les Houches. A JETSET school on ”MHD jet models and constraints”, to be held January 2006, is organized
by J. Ferreira and C. Dougados (FOST).
15.11 Scientific Highlights (2002-2005)
• ”Transport of cosmic rays in chaotic magnetic fields”, Casse Fabien, Lemoine Martin, Pelletier Guy, 2002,
Phys. Rev. D.
The knowledge of the diffusion coefficients of cosmic rays is crucial for astrophysical applications and
especially for astroparticle physics, both for mastering the cosmic ray propagation and the efficiency
of Fermi acceleration. They have been computed with a Monte Carlo simulation as a function of the
cosmic ray rigidity and the spectrum of the magnetic field (characterized by its index and its degree of
irregularities). The Bohm scaling, often assumed in astroparticle physics in the strong turbulence regime,
has been ruled out. The scalings derived for the pitch angle diffusion and for the parallel diffusion with
the ”quasi-linear theory” are extended in an appropriate way in the strong turbulence regime. However
the transverse diffusion coefficient follows a law which is nor Bohm nor quasi-linear, but a law that stems
from the analysis of the spatial chaos of field lines. This result is important to estimate the confinement
time of cosmic-rays in galaxies and in extragalactic jets.
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