Backscattering of electromagnetic and gravitational waves off Schwarzschild geometry

This paper shows that the backscattering of electromagnetic and gravitational waves can be dominant when the radiation is produced very close to a spherical black hole. Numerical investigation shows that almost 50 per cent of the outgoing quadrupole gravitational wave is backscattered for a class of initial data. A similar analysis reveals at least a 20 per cent effect for a dipole electromagnetic radiation. Numerical results confirm theoretical predictions that the backscatter of short wavelength radiation is negligible. In the long-radiation band a rather weak dependence on the wavelength is observed. Our studies are based on the linear approximation. They can be of relevance for the determination of the total energy of backscattering tails and quasinormal modes