New Approaches to the Origin and Dynamics of Magnetic Fields of Cosmic Relevance

摘要

The work supported by this grant focused on turbulent magnetized plasma physics motivated by, but not restricted to, processes in astrophysical plasmas. The work integrated theoretical studies of magnetic field origin and dynamics with astrophysical and laboratory environments. A primary focus of the research was understanding non-linear magnetic dynamo theory. We have, for the first time, produced analytic models that fit fully non-linear 3-D simulations of dynamo action in turbulent plasmas extremely well. Central to the work has been understanding the role of magnetic helicity evolution. In addition to the theoretical work, we have studied dynamo models of specific astrophysical sources and laboratory systems. We have developed non-linear theories for both velocity driven and magnetically driven dynamos. Another focus of the research has been magnetohydrodynamic plasma accretion flows and dynamo-driven outflows and jets. The direct application to astrophysical sources both in the relativistic (active galactic nuclei, gamma-ray bursts) and non-relativistic (stellar outflows) regimes was studied. We also investigated diagnostics for general accretion plasmas around black holes based on how the geometry of the plasma accretion flow determines specific fluorescent Iron line profiles These accretion disks are sites of dynamo action and it is important to know their geometry and to test the paradigms in broad use for explaining the emission from compact accreting systems. We also studied aspects of dynamo theory and particle acceleration in the sun. Over 50 papers have come from this research grant.