Vacuum non-linear electrodynamic polarization effects in hard emission of pulsars and magnetars

The non-linear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum non-linear electrodynamics is obtained. It was shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. Observational possibilities of vacuum birefringence are discussed. The estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy are given. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum non-linear electrodynamics birefringence.