Future Observations of Cosmic Magnetic Fields with LOFAR, SKA and Its Precursors

Abstract

Polarization observations with the forthcoming large radio telescopes will open a new era in the observation of magnetic fields and should help to understand their origin. Low-frequency radio synchrotron emission from the Milky Way, galaxies and galaxy clusters, observed with the new Low Frequency Array (LOFAR) and the planned Square Kilometre Array (SKA), traces low-energy cosmic ray electrons and allows us to map the structure of weak magnetic fields in the outer regions and halos of galaxies, in halos and relics of clusters and in the Milky Way. Polarization at higher frequencies (1–10 GHz), to be observed with the SKA and its precursors Australia SKA Pathfinder (ASKAP) and the South African MeerKAT telescopes, will trace magnetic fields in the disks and central regions of galaxies and in cluster relics in unprecedented detail. All-sky surveys of Faraday rotation measures towards a dense grid of polarized background sources with ASKAP (project POSSUM) and the SKA are dedicated to measure magnetic fields in intervening galaxies, clusters and intergalactic filaments, and will be used to model the overall structure and strength of magnetic fields in the Milky Way. Cosmic magnetism is “key science” for LOFAR, ASKAP and the SKA.