Polarisation in the Pulsar Wind Nebulae

The main goal of our present work is to provide, for the first time, a simple computational tool that can be used to compute the brightness, the spectral index, the polarization, the time variability and the spectrum of the non-thermal light (both synchrotron and inverse Compton, IC) associated with the plasma dynamics resulting from given relativistic magnetohydrodynamics (RMHD) sim- ulations. The proposed method is quite general, and can be applied to any scheme for RMHD and to all non-thermal emitting sources, e.g. the pulsar wind nebulae (PWNe), and in particular to the Crab Nebula (CN) as in the present proceeding. It is here analyzed in detail only the linear optical and X-ray polarization that characterizes the PWNe synchrotron emission in order to in- fer information on the inner bulk flow structure, to provide a direct investigation of the magnetic field configuration, in particular the presence and the strength of a poloidal component, and to understand the origin of some emitting features, such as the knot, whose origins are still uncer- tain. Future work will be necessary to obtain polarization maps in the hard X- and gamma-rays to compare with the actual observations by Integral/IBIS [7]. The complete investigation of the dynamics and synchrotron emission can be found in [5]. In [22] the inverse Compton radiation is treated to disentangle the different contributions to radiation from the magnetic field and the particle energy distribution function, and to search for a possible hadronic component in the emit- ting PWN, and thus for the presence of ions in the wind. If hadronic radiation was found in a PWN, young supernova remnants would provide a natural birth-place of the cosmic-rays around the knee.