Abstract: Plasmas are ubiquitous in astrophysical environments, spanning a range of magnetization states—from the weakly magnetized intracluster medium (ICM) or intergalactic medium in early universe to the strongly magnetized magnetospheres of neutron stars. These regimes exhibit distinct physical processes. In the first part of this talk, I will focus on weakly magnetized plasmas, exploring the origin and evolution of cosmic magnetism in systems like the ICM. By taking into account the effects of nonequilibrium micro-physics of collisionless plasmas on macroscopic astrophysical processes, we demonstrate that “seed” magnetic fields arise spontaneously through kinetic plamsa instabilities under generic astrophysical flows and grow rapidly via plasma dynamo processes. The ab initio production of these dynamically strong fields from an unmagnetized plasma advances a fully self-consistent and predictive explanation of the prevalence of cosmic magnetism. In the second part, I will shift to strongly magnetized plasmas, examining how plasma is loaded into magnetar magnetospheres through the twisting of magnetic flux tubes induced by crustal motions. Radiative particle-in-cell simulations reveal how shear-driven electric fields extract atmospheric particles, forming double-layer structures that efficiently accelerate particles. When an ad-hoc pair-production is prescribed, fast particles can efficiently pair-produce and load the plasma into the magnetosphere.
Bio: Muni Zhou is a Postdoctoral Member at the Institute for Advanced Study (IAS) in Princeton. She earned a BSc in Physics from Zhejiang University in 2016 and a PhD in Nuclear Science and Engineering from MIT in 2022. Starting January 2025, she will join Dartmouth College as an Assistant Professor in the Department of Physics and Astronomy. Dr. Zhou uses a combination of analytical calculations and numerical tools to investigate multi-scale plasma processes in a wide range of space and astrophysical systems, as well as in nuclear fusion devices.
