Polarization of radiation of point-like source reflected from turbulent magnetized atmosphere

¹ Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Apartado Postal 51 y 216, 72840, Tonantzintla, Pue., México e-mail: silant@inaoep.mx
² Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences, 196140 St.-Petersburg, Pulkovo, Russia

Received: 10 October 2007
Accepted: 7 December 2007

Abstract

We consider the multiple scattering of the light from a point-like source located above the semi-infinite electron, turbulent, and magnetized atmospheres. The frozen magnetic field has both the regular and stochastic  components (). The stochastic Faraday rotations due to fluctuations  decrease the intensity of each separate polarized beam (the extinction factor is proportional to ). This decrease at large  dominates the usual decrease () caused by summing beams with very different Faraday's rotation angles. This effect changes the spectrum of polarization degree as compared with what is influenced by the regular magnetic field. We calculated the integral (observed) polarization of the reflected radiation with the inclusion of unpolarized radiation going directly from the point-like source. We present the observed polarization for various degrees of true absorption of the radiation into the atmosphere and the values of magnetic energy fluctuations. The spectra of polarization in the optical (–1 ), infrared (–5 ), and X-ray (–50 keV) regions of the wavelengths are presented. We discuss the possibility of estimating parameters of magnetic field fluctuations from the observation of the spectra of polarization in AGNs with the X-ray excesses and in the turbulent accretion disk in NGC 4258.