19 March 2009

Speaker: Anatoly Spitkovsky (Princeton University)

Title:The Physics and Astrophysics of Collisionless Shocks

Abstract:Nonthermal emission from a variety of astrophysical sources, including relativistic jets and supernova remnants, is often attributed to collisionless shocks. These shocks are inferred to accelerate particles and in some cases strongly amplify magnetic fields. How this happens remains to be clarified through both theory and observations. In this talk, I will present a summary of recent progress in theoretical modeling of collisionless shocks using first-principles plasma simulations. I will discuss the internal structure of relativistic and non-relativistic shocks, concentrating on the conditions necessary for particle acceleration. I will present simulations which show ab-initio Fermi acceleration of particles from the thermal pool to power-law distributions and set constraints on the shock acceleration efficiency and geometry. Other results that will be discussed include the amplification of magnetic fields by accelerated particles through streaming instabilities, and the electron-ion temperature equilibration in shocks. I will conclude with the applications of shock simulations to the physics of gamma-ray bursts, pulsar wind nebulae, and supernova remnants.

Video of the Presentation (Talks can be viewed with RealPlayer. Free download is available from www.real.com )