Rapid variability in optical polarization of the quasar-like object OJ287

The authors report here observations of rapid and strong variations in the degree of linear polarization of the optical flux of OJ287. It is concluded that if the radiation observed from the variable component was of synchrotron nature, then there must be a high degree of relativistic beaming in OJ287. On the other hand, if the variable flux is assumed to be the inverse-Compton scattered flux and relativistic effects are not invoked, OJ287 must have a very compact central source, probably a black-hole accretion-disk system. (author)