Key physical processes in the galactic dynamos

Anvar Shukurov, anvar.shukurov@newcastle.ac.uk, University of Newcastle, UK

Abstract
The fundamental physical process underlying astrophysical dynamos is magnetic induction, whose specific manifestations depend on the nature of the plasma flow. Random flows (turbulence) typical of most astrophysical objects, including galaxies, can result in an exponential amplification of magnetic field at both the global scale of the object (the mean-field dynamo) and at the turbulence scales (the fluctuation dynamo). Recent progress in galactic dynamo theory and observations is due to our better understanding of the nonlinear saturation of the mean-field and fluctuation dynamos, and of the detailed properties of the associated random magnetic fields. A fascinating new avenue of research is the dynamo action in the multi-phase interstellar medium and the effects of widespread shocks on the structure of interstellar magnetic fields. This talk will present the current state of the theory and observations of interstellar magnetic fields in spiral galaxies with emphasis on the physical processes involved and their observational diagnostics.