Comptonization of low-frequency radiation in accretion disks Angular distribution and polarization of hard radiation

In accretion disks the angular distribution and polarization of hard radiation forming via Comptonization, i.e., multiple scatterings in the disk, depend only on the optical thickness of the disk and are independent of either the photon frequency or the geometric distribution of low-frequency photons. This paper presents calculations of the angular distribution and polarization made for several values of the optical thickness of disks, for the case of the Thomson scattering. The method of successive approximations over the number of scatterings was employed in the calculations, without taking into account the frequency dependence of the scattering cross-section and indicatrix. Specific astrophysical applications of the results obtained are discussed. A simplified theory of electron temperature dependence on the vertical coordinate in the disk is given. The density distribution over the vertical coordinate in the radiation-dominated disks is derived.