The Global Structure of the Galactic Magnetic Field from Rotation Measures of Extragalactic Sources

摘要

Using the two latest sets of Rotational Measures (RMs) of extra-galactic radio sources, namely the NRAOVLA Sky Survey Rotation Measures Catalogue, and a compilation by Kronberg and Newton-McGee, we inferred theglobal structure of the Galactic Magnetic Field (GMF). We considered GMF models consisting of two components:spiral disk and halo. The parameters of these components were determined by fitting results of simulations with differentmodel field geometries to the observed RMs. We found that the model consisting of a symmetric (with respect to theGalactic plane) spiral disk and anti-symmetric halo fits the data best, and reproduces the observed distribution of RMsover the sky very well. Our results favor small pitch angles around 5and an increased vertical scale of electrondistribution, in agreement with some previous studies. Based on our fits, we present two benchmark models suitable forstudies of cosmic ray propagation, including the ultra-high energies.