Nov 11, 2020

Speaker: Niccolò Bucciantini (Osservatorio Astrofisico di Arcetri)

Title: Pulsar Wind Nebulae: a wondrous astrophysical lab.

Abstract: Pulsars and the associated nebulae are perhaps one of the most fascinating high-energy astrophysical environment. The combination of strong magnetic field, and rapid rotation, leads to copious pair production making these objects one of the main contributors to anti-matter in the Galaxy. This magnetically dominated ultra-relativistic pair outflow interacts with the surrounding medium, either the parent SNR in young systems or the ISM for old objects, leading to the formation of synchrotron and TeV emitting bubbles, the Pulsar Wind Nebulae, among which the most famous is the Crab Nebula. There, particles are accelerated to non-thermal distributions with almost 100% efficiency. These systems offer us a unique lab to investigate in detail, pair-production, relativistic outflow acceleration, magnetic dissipation and particle acceleration. In the last decade a large effort has gone toward modelling of these objects, and today, we can perform full 3D models that enable us to use them as "imagers" of the pulsar wind. Open questions still remain about the importance of turbulence, and the structure of magnetic field. I will review the current status of our understanding, and how far our modelling has progressed in the last years. I will also discuss the upcoming IXPE mission aimed at getting the fist space resolved X-ray polarimetric maps of the brightest PWNe, and to constrain the magnetic field geometry, close to the acceleration region.