Pulsar wind nebulae are fascinating systems, powered by the central rotating compact star, emanating a wind in the form of a relativistic, magnetized, and cold plasma that fills the nebula. They are visible as bright non-thermal sources in a very broad range of energies, from radio to gamma-rays. Observed morphologies vary with the evolutionary phase, with middle-aged and old systems strongly affected by the interaction with the ambient medium. Modeling of these sources requires some carefulness when going through the various phases, with a comprehensive description still lacking. Pulsar wind nebulae had been for a long time thought to contribute substantially to the positron excess in the CR spectrum at Earth -- potentially being the primary sources. In the last years, numerous evidence for efficient particle leakage by aged nebulae had been collected, showing up as quasi-monochromatic misaligned jets at X-rays in some cases, or in the form of extended TeV halos in others, reanimating somehow the interest in this class of objects. Here I will review our present knowledge of pulsar wind nebulae models through their different ages.
Organizer: Matteo BUGLI