Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Polarimetry : a detective magnifying glass to probe astronomical objects

lundi 14 janvier 2019, par Frédéric Marin (Observatoire de Strasbourg)

Mercredi 23 janvier 2019 à 11h00 , Lieu : Salle de rĂ©union du bâtiment 14

One of the main challenges in astrophysics is that we are trying to understand cosmic objects without fully spatially resolving them. Many small scale details remain elusive. Since we do not have yet a complete knowledge of both the large scale and small scale structures, composition or magnetic topology of our favorite cosmic objects, we are ultimately struggling to understand the physical mechanisms that govern them. High-angular, high-resolution imaging, spectroscopy, timing or interferometric techniques provide us with exquisite details but they all remain poorly sensitive of the morphology, magnetic fields or gravitational effects governing the small scales. To reveal the truth, polarimetry is probably our best tool. As we will see this during the presentation, polarimetric techniques are highly sensitive to the smallest geometric details, from the morphology of accretion disks to the thinnest shells of supernova remnants. Polarization can also reveal the magnetic topology in solar flares, the magnetic reconnections in disk’s atmospheres or the synchrotron emission in jets. Starting the presentation with a detective enigma, I will then review what polarimetry can do and what are the expected discoveries to be made in virtually all astrophysical fields thanks to the new generation of polarimeters that will arrive in the close future.