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A new era in the study of interstellar magnetic fields

Marta Alves

Magnetism is a fundamental force of nature. Since interstellar magnetic fields were discovered in our Galaxy in 1949, it has been established that magnetism is pervasive in the Universe. Planets, stars, and galaxies all show the presence of magnetic fields, which span a large range in strength and change considerably in structure. Throughout the years we have inferred the properties of galactic magnetic fields from a variety of observational methods. Not only from observations but also from a theoretical point of view, it became clear that magnetic fields are a vital constituent of the interstellar medium, playing a critical role in the lifecycle of matter.
In this talk I will start by reviewing the classical observational methods of interstellar magnetic fields and what they have taught us about our Galaxy. I will present the all-sky submillimetre observations by the Planck satellite, which gave us a unique view of the Galactic magnetic field. Then I will discuss two methods that allow us to study the Galaxy in 3D : stellar polarimetry combined with Gaia astrometry, and Faraday tomography. The latter is a new and powerful technique, which is being applied to radio data, from e.g. LOFAR, and revealing a bewildering variety of structures in the Galactic diffuse interstellar medium. While exploiting these new radio data - a true gold mine - we are already looking ahead to SKA and to what this great upcoming radio telescope will disclose on our Galaxy.