XMM-Newton observations of PSR B1259 63 near the 2004 periastron passage

We present here the results of new XMM-Newton observations of the PSR B1259-63 system during the beginning of 2004, as the pulsar approaches the disc of the Be star. We combine these results with earlier X-ray data from BeppoSAX, XMM-Newton, and ASCA. The X-ray light curve looks similar to the radio light curve with a rapid increase in the flux around the time of the disc crossing. This supports a model in which the X-ray emission from the system is due to inverse Compton scattering of the pulsar wind relativistic particles with moderate Lorentz factor γ ∼ 10-100 on the Be star soft photons.