Guy Pelletier

TL;DR: In this paper, a general theory for the origin and collimation of hydromagnetic winds from the surfaces of Keplerian accretion disks that surround central objects such as young stellar objects (YSOs) or black holes is presented.

TL;DR: In this article, the growth rates of the following beam plasma instabilities seeded by the accelerated and reflected particle populations are investigated: Weibel and filamentation instabilities, as well as the Cerenkov resonant instabilities with electrostatic modes; for a magnetized shock, the Weibel instability and the resonant Cererkov instabilities in the longitudinal electrostatic mode, aswell as the Alfven, Whisler and extraordinary modes.

TL;DR: In this paper, the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g., gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae.

TL;DR: In this article, it was shown that Fermi acceleration at an ultrarelativistic shock wave cannot operate on a particle for more than 1 FER cycles if the particle's Larmor radius is much smaller than the coherence length of the magnetic field on both sides of the shock.

TL;DR: In this paper, a model for relativistic beam formation in active galactic nuclei is proposed, in which electrons and positrons are generated by pair cascade on the UV photons of the accretion disk.