A tribute to Guy Pelletier.

14-18 October 2013

About Guy Pelletier

Guy Pelletier is an emeritus professor at the Institute of Planetology and Astrophysics of Grenoble (IPAG), belonging to the Observatoire de Grenoble (CNRS/INSU, Université Joseph Fourier). He first studied plasma physics and worked on plasma turbulence in hot plasmas, with applications to tokamaks. Then he turned to astrophysics, starting to work on the structure of extragalactic radio sources. He proposed an original model of extragalactic jets, the "two-flow" model, in which he suggested that the radio jets could be formed by a double structure, a jet of ordinary matter, confining an electron-positron beam. The development of gamma-ray satellites and Atmospheric Cerenkov Telescopes led to the discovery of intense high energy emission from Active Galactic Nuclei, and the two-flow model was shown to reproduce very well the observed emission. Belonging to the HESS collaboration, Guy Pelletier participates actively to these discoveries. He also worked on magnetohydrodynamical models of accretion-ejection structure, developing a coherent view in which the ejection of matter was linked to the accretion process through the magnetic field. He studied also the particle acceleration mechanism, particularly in relativistic shocks, in order to understand the generation of ultra-high energy cosmic rays, especially in gamma-ray bursts. He has been awarded by a nomination to the Institut Universitaire de France, and has been a member of several important scientific committees.