Muni Zhou, Dartmouth College
When
Refreshments served in the 3rd Floor Atrium
TAP Plasma Physics Initiative Lecture
Muni Zhou, Dartmouth College
Visit Dates: March 15-21, 2026
Title: Genesis, amplification, and relaxation of cosmic magnetic fields
Abstract: Astronomical observations suggest pervasive, dynamically important magnetic fields in our Galaxy and the intracluster medium, yet their origin remains a long-standing question in astrophysics and cosmology. It is widely believed that such fields first arose as weak “seeds” generated by cosmic batteries and were subsequently amplified by turbulent plasma flows to current levels via the dynamo process; however, a complete understanding of these processes in weakly collisional plasmas, as well as the sustenance of magnetic fields once turbulent stretching subsides, is still lacking. This work presents a unified paradigm for the origin and evolution of cosmic magnetism by incorporating the effects of nonequilibrium microphysics of collisionless plasmas into macroscopic astrophysical processes. Using analytical theory and first-principles numerical simulations, it is demonstrated that seed magnetic fields can spontaneously emerge under generic turbulent motions through kinetic plasma instabilities, implying that cosmic plasmas are ubiquitously magnetized. The cross-scale, nonlinear coupling between microscopic magnetic fields and macroscopic flows enhances turbulence and accelerates the plasma dynamo, rapidly amplifying the field to energy equipartition with the turbulent flow. The subsequent relaxation of these fields after turbulent stretching subsides is regulated by pressure-anisotropy-driven instabilities. The ab initio production of equipartition-strength fields from an initially unmagnetized plasma, together with their relaxation, provides a predictive explanation for the prevalence of cosmic magnetism, a key target of upcoming observations such as those by the Square Kilometer Array.
Bio: Muni Zhou is an Assistant Professor in the Department of Physics and Astronomy at Dartmouth College. She earned her B.S. in Physics from Zhejiang University and received her Ph.D. in Nuclear Science and Engineering from MIT in 2022. Before joining Dartmouth College in 2025, she was a Presidential Postdoctoral Research Fellow at Princeton University and a Postdoctoral Member at the Institute for Advanced Study. She uses a combination of analytical theory and numerical experiments to study fundamental plasma problems including turbulence, magnetic reconnection, magnetogenesis, and dynamo processes.
Links: Muni Zhou's Personal Website