First light of modern X-ray polarimetry
December 9, 2021 marks the date of the launch of the very first modern X-ray polarimeter, more than 40 years after the OSO-8 mission. IXPE (Imaging X-ray Polarimetry Explorer) has just opened a new window in high energy astronomy, adding polarimetry to temporal, spectral and imaging techniques to study the physical and geometric properties of celestial sources. Indeed, almost all classes of X-ray emitting sources can be probed by polarimetry. Among them: binaries of neutron stars or black holes, X-ray pulsars, magnetars and active galactic nuclei (both radio-quiet and radio-loud AGNs). During this seminar, I will present how X-ray polarimetry (thanks to IXPE but also to other future X-ray and gamma-ray polarimeters) will allow us to map magnetic field topologies and turbulence both in supernova remnants — clarifying their role in the acceleration of galactic cosmic rays — and in pulsar wind nebulae –highlighting their complex morphology –. We will also examine the first results of IXPE in the field of the formation, evolution and composition of jets from black holes, not forgetting to look at our closest relative Sgr A* which sits at the center of the Milky Way, whose last centuries of history may perhaps be probed by X-ray polarization imagery.