Abstract
We study the spectrum and polarisation properties of reflected X-ray emission from accretion discs illuminated by a corona in AGNs. In order to model polarisation induced mainly by scattering off free electrons we used the Monte Carlo radiative transfer code STOKES developed by Goosmann & Gaskell (2007), Marin et al. (2012, 2015) and Marin (2018).
The structure of the disc, modelled as a constant density slab, has been computed with the code for optically thick and hot photo-ionized media TITAN (Dumont et al., 2003). The resulting simulated spectra locally emitted by the accretion disc in 0.1-100 keV energy band are compared to the results obtained by different radiative transfer code XILLVER (Garcıa et al., 2013).
In addition to the spectral output, STOKES code provides also the polarisation degree and polarisation angle of the outcoming radiation that depend on geometry of scattering, ionisation of the disc, photon-index of the primary power-law radiation or the initial polarisation of the primary radiation. These unique polarisation simulations are compared to computations using the Chandrasekhar's analytical formulae.