Unconventional gravitational excitation of a Schwarzschild black hole

Besides the well-known quasinormal modes, the gravitational spectrum of a Schwarzschild black hole also has a continuum part, i.e., a branch cut in Greenʹs function, on the negative imaginary frequency axis. The latter is studied numerically for quadrupole waves. The results show unexpected striking behaviour near the algebraically special frequency (omega) = -4i. This reveals a pair of unconventional damped modes very near (omega) , confirmed analytically.