Effects of Magnetic Coupling on Temperature Profile of Black-Hole Accretion Disc

We propose a model of the magnetic coupling (MC) of a rotating black hole (BH) with the surrounding accretion disc in order to study the radial temperature profile in the inner region of the disc, in which a linear map from the angular coordinate on the BH horizon to the radial coordinate on the thin disc is given by closed magnetic field lines. The MC power and torque are derived by using a modified equivalent circuit. It is shown that the MC effects on the temperature profile are related intimately to the BH spin, resulting in the variation of the value and the position of the peak temperature. It turns out that the value range of the color temperature of the disc is extended by the MC effects.