Global Trapped Oscillations of Relativistic Accretion Disks

Abstract Axially symmetric, isothermal pulsations of a geometrically thin disk rotating around a nonrotating relativistic object are investigated. The disk is assumed to be isothermal in the vertical direction and to have a constant vertical scale height. It is found that there exist global pulsation modes trapped in an inner region of the disk. Eigenfrequencies of the modes are in the range of 0 to κmax, where κmax is the maximum value of an epicyclic frequency in the disk. For an oscillation to be trapped in the disk, the eigenfunctions must have at least one node in the vertical direction. The trapping is related to the fact that, in relativistic disks, the radial distribution of the epicyclic frequency has a maximum at a certain radius. The results suggest that the presence of global trapped oscillation modes is a general characteristic of thin relativistic disks. The oscillation period obtained is briefly compared with observations.

Перевод пока недоступен