INFLUENCE OF STRINGS WITH AXIONIC CONTENT ON THE POLARIZATION OF EXTRAGALACTIC RADIO-SOURCES

It is shown that the axion concentrated in electroweak strings which a re consequently stabilized may produce a rotation of the polarization angle of radiation from extragalactic sources larger than that caused by a background field, and that axionic walls attached to global strin gs have an effect which depends on the frequency. We discuss the valid ity of the classical and quantum treatments of radiation and indicate that the latter produces conversion of linear into circular polarizati on. We describe possible anomalies in the observations which might sug gest these influences of the axion.