POSSUM: Polarisation Sky Survey

of the Universe's Magnetism

The Australian Square Kilometre Array Pathfinder (ASKAP) is a next-generation radio telescope about to commence operations in outback Australia. ASKAP's large instantaneous field-of-view allows it to survey the sky vastly faster than is possible with existing radio telescopes, allowing us to address fundamental questions about the origin and evolution of the Universe.

The "Polarisation Sky Survey of the Universe's Magnetism" (POSSUM) is one of the eight major surveys to be undertaken on ASKAP. In POSSUM, we are using ASKAP's unique survey capabilities to measure the Faraday rotation of three million extragalactic radio sources over 30,000 square degrees, thereby dramatically improve our understanding of astrophysical magnetism. With these data, we aim to determine the 3D geometry of the Milky Way's magnetic field, to test dynamo and other models for magnetic field generation, and to carry out a comprehensive census of magnetic fields as a function of redshift in galaxies, in clusters and in the overall intergalactic medium.