Self-Trapping of G-Mode Oscillations in Relativistic Thin Disks, Revisited

We examine by a perturbation method how the self-trapping of g-mode oscillations in geometrically thin relativistic disks is affected by uniform vertical magnetic fields. Disks which we consider are isothermal in the vertical direction, but are truncated at a certain height by presence of hot coronae. We find that the characteristics of self-trapping of axisymmetric g-mode oscillations in non-magnetized disks is kept unchanged in magnetized disks at least till a strength of the fields, depending on vertical thickness of disks. These magnetic fields become stronger as the disk becomes thinner. This result suggests that trapped g-mode oscillations still remain as one of possible candidates of quasi-periodic oscillations observed in black-hole and neutron-star X-ray binaries in the cases where vertical magnetic fields in disks are weak.