Corotation Resonance and Diskoseismology Modes of Black Hole Accretion Disks

Understand

We demonstrate that the corotation resonance affects only some non-axisymmetric g-mode oscillations of thin accretion disks, since it is located within their capture zones.

• Using a more general (weaker radial WKB approximation) formulation of the governing equations, such g-modes, treated as perfect fluid perturbations, are shown to formally diverge at the position of the corotation resonance.
• A small amount of viscosity adds a small imaginary part to the eigenfrequency which has been shown to induce a secular instability (mode growth) if it acts hydrodynamically.
• The g-mode corotation resonance divergence disappears, but the mode magnitude can remain largest at the place of the corotation resonance.