Abstract

Orbiting features near a black hole can cause variability in optical/UV and X-ray bands with quasi-periodic signatures. The variable flux is derived in Kerr geometry including the following relativistic effects: light bending, time delay, Doppler and gravitational shifts and aberration. Themodel can be used as a distinguishing timing signature to identify types of accretion disks in active galactic nuclei and X-ray binaries and to constrain the black hole mass and spin.