The Milky Way’s magnetic field has coherent structures on Galactic scales, following spiral arms but also Galactic outflows. It also has a turbulent component, which influences the galactic ecosystem in many ways, such as delaying star formation, isotropizing Galactic cosmic rays, and providing significant pressure component.
These magnetic field components can only be detected indirectly, through the signature they leave on various kinds of radiation and particles, observations of which are fitted to models of the Galactic magnetic field. Traditionally, radio polarimetry is most used to probe Galactic magnetic fields, with radio detectors in frequency ranges from LOFAR to Planck giving unique information.
I will discuss some of the recent progress in this field, and our new project called IMAGINE, which aims to combine all different observational tracers and prior information to build a next-generation model of the Galactic magnetic field.