Two-dimensional, relativistic, MHD simulations of pulsar-wind powered nebulae
provide strong constraints on the properties of the winds themselves. In
particular, they confirm that Poynting flux must be converted into particle
energy close to or inside the termination shock front, emphasising the puzzle
known as the σ paradox. To distinguish between the different possible
resolutions of this paradox, additional observational constraints are required.
In this paper, I briefly discuss two recents developments in this respect: the
modelling of high time-resolution optical polarimetry of the Crab pulsar, and
the detection of the pulsar/Be star binary PSR 1259-63 in TeV energy
gamma-rays.Comment: Paper presented at the workshop on "Stellar End Products", Granada
13-15 April 200