Variation of Magnetic Field Strength in the Galactic Halo

Determine the dependence of the Milky Way halo magnetic field strength on Galactocentric radius and vertical height above and below the Galactic plane, focusing specifically on characterizing how the field strength varies with radius and height to constrain the detailed properties of the Galactic halo magnetic field.

Background

The presence of a large-scale magnetic field in the Galactic halo is supported by the antisymmetric Faraday rotation sky and modeling of toroidal structures. Recent work using pulsar rotation measures and extragalactic source RMs has provided the first quantitative estimates of the extent of magnetic toroids in the halo and set a lower bound on the magnetic field scale height.

Despite these advances, quantitative characterization of how the halo magnetic field strength varies with Galactocentric radius and vertical height remains insufficiently constrained, and improved measurements—particularly from new pulsar discoveries and RM determinations—are needed to refine the spatial dependence of the halo field.