Speaker
Description
The relation between magnetic field strength, B, and gas density, n, in the interstellar medium is of fundamental importance to many areas of astrophysics, from protostellar disks to galaxy evolution. We present and compare a brand new multi-parameter Hierachical Bayesian analyses of the B-n relation for a comprehensive observational data set, as well as a large body of numerical MHD simulations. We extend the original Zeeman relation with 700 observations that use the Davis-Chandrasekhar-Fermi method and find the existence of power-law exponent in the diffuse ISM and a change in the position of the break point, which now appears at higher densities. We also perform a separate analysis on 19 numerical magnetohydrodynamics simulations that cover a wide range of scales, resolutions, initial conditions, and completed with a variety of codes: AREPO, Flash, PENCIL, and RAMSES. The power law exponents derived from the simulations depend on several physical factors including: dynamo effects, time scales, turbulence, and the initial seed field strength. In particularare we find that the simulations that trace the observed density range best, the evolved dwarf galaxies and Milky Way like galaxy simulations match the observevational result closest with variability in the diffuse gas exponent.
