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.