Theoretical Physics Colloquium: Dmitri Uzdensky

Abstract: Relativistic compact astrophysical objects --- neutron stars and black holes --- display spectacular phenomena like bright high-energy flares, powered by nonlinear collective plasma processes such as magnetic reconnection, shocks, turbulence. While traditional (space, solar, lab) plasma research has given us great insight into these processes, the physical plasma conditions near black holes and neutron stars are so extreme that conventional intuition often fails and a richer physics framework is required. Extreme astrophysical plasmas are relativistic, interact strongly with high-energy radiation, and may be subject to QED (e.g., pair-production) effects. Understanding how collective plasma processes (e.g., waves, instabilities, turbulence, magnetic reconnection) operate in the presence of this “exotic” physics is the main goal of Extreme Plasma Astrophysics. Exploration of this new frontier of theoretical physics is now progressing rapidly thanks to the confluence of strong observational motivation, concerted theoretical efforts, and the advent of radiative/QED relativistic kinetic plasma simulation codes. Novel laser-plasma experiments will soon also contribute to this revolution.  I will review recent advances in this burgeoning new field, focusing on relativistic radiative magnetic reconnection and turbulence, with applications to neutron-star magnetospheres and accreting black holes. I will also outline key theoretical challenges and promising future directions of Extreme Plasma Astrophysics.