Kelvin-Helmholtz instability at the interface of a disc-corona system

We study Kelvin-Helmholtz (KH) instability at the interface of a disc and corona system by doing a linear perturbation analysis. The disc is assumed to be thin; however, the corona is considered to be nearly quasi-spherical because of its high temperature. Under these circumstances, the interface is subject to the KH instability for a given set of the input parameters. Growth rates of the KH unstable modes are calculated for a wide range of the input parameters. We show that for a certain range of the perturbations, the unstable KH perturbations are growing with time-scales comparable to the inverse of the angular velocity of the accretion disc (dynamical time-scale). Thus, KH instability at the interface of a disc-corona may have enough time to affect the dynamical structure of its underlying accretion disc by possible exchange of the mass, angular momentum or even energy. Our linear analysis shows that KH instability may provide a mechanism for such exchanges between a disc and its corona.