Rapid polarization variability in intense sources

Abstract

We have recently reported the polarization changes of the intense electromagnetic radiation, in active galactic nuclei and pulsars, due to stimulated Raman scattering. In this paper, we show that the incident and the Raman-scattered radiation, when superimposed, exhibit highly complex and variable polarization patterns, some of which could account for the observed polarization variability in intense sources. Further, if the ratio of the frequencies of the incident and the scattered radiation is an irrational number, the electric field of the superimposed radiation traces a quasi-periodic rotation. The modulation of the Raman-scattered sideband modes, with even small perturbations due to the thermal radiation or the Raman cascade, would lead to chaotic rotation of the electric field of the superimposed radiation.