Geometrically thick disk model (in red) surrounding a compact object (black disk) of mass M. The disk has an inner radius r_in, where the electron number density and temperature are n_e, in and T_e, in. The number density scales as r⁻² and the temperature as r⁻¹. All quantities are independent of the height z. The opening angle of the disk is called θ_op. Here and throughout the article, the compact object and accretion disk spins (black and red arrows, respectively) are assumed to be aligned. The inclination angle i between the spin axis and the line of sight is shown in green.