Equiangular Spiral Modes of Power Law Disks

The stability of self-similar power-law disks to non-axially symmetrical disturbances of zero frequency (omega = 0) is discussed. It is established that marginally unstable modes either have (omega = 0) or consist of continua with modes of all frequencies becoming unstable together. A careful study of all modes close to omega = 0 yields a remarkable conclusion.