Speaker
Description
The standard scenario of a geometrically thin, planar accretion disk can be violated by a number of effects that must operate in astrophysically more realistic schemes. Even within a highly simplified framework of an axially symmetric (2D), steady, Keplerian accretion, the radial structure can be different from the predictions of the classical Shakura-Sunyaev theory. For example, stars and stellar-mass black holes can be embedded within the accretion disk, where they may induce formation of gaps in the radial density profile. Also, an intermittent supply of gas may lead to individual accretion rings rather than an extended disk. In this contribution we focus on the theoretical profiles of the spectral line produced by reflection of the surface of both gappy accretion disk and ring-like structure residing near a black hole. While the smooth accretion disk leads to a typical, double-horn shape with unequal wings due to Doppler boosting and an additional peak due to the lensing amplification, gaps and rings give rise to a more complex dependence which reflects the location and the radial extent of the inhomogeneities in the accretion flow.