Plasma Seminar


Guest Speaker: Vladimir V. Zhdankin (Princeton University)
Talk Title: "Kinetic turbulence in relativistic and radiative plasmas"
Date: Friday October 4, 2019, 1:00-2:00 pm
PAB PAB 4-330 (map)
Abstract: Turbulence plays a fundamental role in high-energy astrophysical systems, where the constituent plasmas are often collisionless and relativistic. The plasmas in such systems are energized by turbulent cascades and cooled by radiative emissions. I will describe recent numerical and theoretical progress on understanding turbulence in this physical regime, based on results from particle-in-cell simulations of driven turbulence in relativistic and radiative plasmas. In particular, I will consider the consequences of radiative cooling via external inverse Compton emission, of sufficient strength to balance the external energy injection. Radiative cooling efficiently thermalizes the particle population, with the resulting quasi-thermal energy distributions well fit by stochastic acceleration models. In the high magnetization regime, the high-energy particles (and hence the emitted photons) exhibit a highly anisotropic momentum distribution, characterized by intermittent beams aimed in random directions. These kinetic beams appear to be an outcome of localized magnetic reconnection and may explain rapid flares in astrophysical systems such as blazar jets.