On the polarized flux density synthesis and on the observations of the long time variability (evolution) of the extragalactic objects.

A method of polarized flux density synthesis for the observation of extended emission sources with a centrosymmetric polarization pattern is presented. It is based on the optimal polarization-spatial filtering of their images and can simultaneously increase both the dynamic range and the signal-to-noise ratio of optically thin scattered halos around compact emission sources. The feasibility of using such a synthesis in the search for cosmological halos (light echos of high-redshift QSOs and AGNs) on the background of intergalactic electron gas and for observations of their past luminosity evolution on the time scale of 10-million to 100-million years is investigated.